"Also from the accountants perspective if the client is not willing to pay as they go, one has to ask - do they intend to pay at all?"
I think thats unfair, if I do a job once a year (as my accountant does) then I expect to get paid for that job when it is done, once a year. I wouldn't use an accountant who wanted monthly payments upfront, end of story - as I said I divide what I think the bill will be basd on historical data, stick it into a reserve savings account, get my 0.25% or whatever it is these days and pay the bill in full when it arrives.
I, like others prepare everything, VAT. P35, Self assessments, P&L, balance sheet so my accountant needs only to check and put the figureds into HIS software to produce the 'glossies'.
I think in the 12 years I have used him, I may have called him one a year in addition to the annual accounts conversation, and for the fees charged for checking, a small amount of data entry and producing 6 sets of accounts, his annual fee covers his title (chartered) more than the actual time spent doing my accounts.
Thats said, I am not belittling my accountant at all, he calls in for coffee and brings the biscuits, he is a genuinely good person, offers advice at year end if he feels it appropriate and ribs me about my 'OCD accounting' as he says I worry too much about the little oddities that seem to escape - pennies due to rounding etc!