A decade or so ago, most investment trust managers ran regular savings schemes allowing monthly or annual purchases of their shares free, or for a nominal charge.
Now, however, a growing number of trusts no longer offer their own regular savings schemes, preferring instead to outsource the service.
There are two main reasons for this. First, investment trusts are becoming more popular, sparked by regulatory changes forcing advisers to consider them for clients, by magazines such as Money Observer highlighting their attractions, and by a more single-minded focus on performance by their managers.
The second and perhaps more important reason is the growth of share platforms, which has made investing in shares - whether as a one-off or a regular purchase - much easier and cheaper for retail investors.
So have company-administered savings schemes had their day, or are there still advantages to investing directly with a trust?
The key advantage is cost: where they are offered, direct savings schemes are generally very cost-effective. Details of the costs are shown in the table below (click to enlarge), but here are some highlights.
Aberdeen Asset Management and Baillie Gifford, two of the biggest investment trust managers, have no annual fee or dealing costs save the stamp duty payable on any share purchase on their share plans, although there are annual fees - respectively £24 and £32.50, plus VAT - for savings made via an Isa.
Witan charges a management fee of £30 a year for its share plan or Isa, and a flat fee of £15 for investing a lump sum, but has no fees - again other than stamp duty - for regular savings.
Compare that with Alliance Trust Savings (ATS), Alliance Trust's wholly owned investment platform. It is named as administrator of the two Artemis investment trusts, Personal Assets Trust and Standard Life's stable of trusts, as well as running its own regular savings plan.
There, the annual administration fee is £7.50 per month, or £90 a year, and the dealing fees are £12.50 for a sale or purchase made online - rising to £40 if by post or telephone.
Sara Wilson, head of platform proposition at ATS, points out that if investments are made by monthly direct debit - minimum £50 per month - the dealing fee falls to £1.50 per trade.
Of course, investors need not use ATS but can choose any of the other platforms, most of which offer a regular investment facility. Research by Aberdeen Asset Management in 2015 found that savings plans accounted for just under 9 per cent of investment into trusts.
Hargreaves Lansdown was the most popular platform among investment trust investors, although Interactive Investor, Fidelity, Barclays Stockbrokers and ATS all have a reasonable share of the market.
Justin Modray, founder of website Candid Money, says: 'The growth of online stockbrokers and investment platforms is starting to make bespoke investment trust savings schemes redundant.
'And most investment trust managers are only too happy to offload their schemes, as they can be both time-consuming and expensive to run.'
Even the companies with the most attractive savings plan schemes wonder whether they will remain worthwhile. Baillie Gifford has 20,000 savings plans accounting for around £800 million across its seven trusts, and levies no charges other than stamp duty.
James Budden, director of retail marketing and distribution, says that the regulatory burden of holding client money and sponsoring the schemes is high.
'It creates a considerable and disproportionate workload within a relatively small area of the firm's business - £800 million from £145 billion under management. Saying that, the schemes continue to be popular with investors, so we carry on providing them.'
Despite its low cost, Baillie Gifford's scheme is seeing considerable outflows to platforms. 'IT savings schemes are very limited in comparison as they date back to the 1990s,' says Budden.
'We see a number of transfers out to platforms each month and you can't blame investors for seeking a more all-encompassing service.
'[These schemes] have succeeded in encouraging and giving (small) investors an efficient way of accessing some great investments.
'Scottish Mortgage, for instance, has Baillie Gifford savings schemes as its biggest holder with 12 per cent. But nowadays it is the platforms which are providing this and offering a better service on the whole.'
Piers Currie, group head of brand at Aberdeen, says: 'Self-directed investors now have a lot of visibility of choice and we have seen an enormous upsurge of buying in investment trusts by self-directed investors through direct platforms, led by HL, but also other providers such as Interactive Investor, traditional execution-only brokers like Barclayshare and other providers.
'Increasingly, investors pick the platform that is convenient for them. They may transact through a platform to aggregate multiple manager funds, or use several platforms.
'But then they call our manager call centres too for detail on dividends or queries about the fund, or to receive a copy of an annual report which platforms may not provide to them.'
Direct investment schemes are still popular, however. Aberdeen's are now worth more than £500 million and Witan's £335 million, while Baillie Gifford's holds £800 million.
But Modray warns against joining such a scheme merely on the basis of price. 'I would avoid direct savings schemes that tie you to a specific trust, unless it's one you wanted to buy in any case. '
Investing via a platform means that you can select from a wide range of trusts, switching between them as performance and investment conditions change.
Moreover, those who regularly use the same platform - and the majority will do so - can see all their holdings in one place, allowing them to more easily track performance relative to others, dividend payments, annual meeting dates and so on at a glance.
Researching which platform to use is, however, just as important as researching which investment product to buy. Charges vary widely: while ATS and Interactive Investor charge a flat fee, others such as Hargreaves Lansdown charge a percentage fee although usually there is a cap.
Dealing fees will also vary, and often depend on the number of trades conducted in any one month, while administrative fees for Isas and direct holdings can also differ.
Wilson at ATS says that its flat fee makes its platform for portfolios of £30,000 competitive and it is 'very competitive' at £50,000 and upwards - its average portfolio size is £75,000.
Modray says: 'For lump-sum investments a low-cost online stockbroker such as x-o.co.uk or SVS XO is likely to be the most cost-effective route, as you'll simply pay low one-off dealing fees.
'However, they don't offer reduced dealing fees for monthly savings, so they start to look expensive for regular savers. This is where investment trust savings schemes could traditionally offer better value.'
His website, comparefundplatforms.com, allows investors to select the most cost-effective option depending on factors such as the investments they want to hold, number of trades and size of portfolio.