It depends whether or not people will be honest - bit like polls on "how much do you earn".
If people were really honest and included all travelling, quoting, cleaning, admin, maintenance, stock replenishment (trip to the shops!!), etc etc AND they added in the hours that they purchase from elsewhere (accountant, leaflet dropper etc) then it might prove useful. Like many self employed people the actual hours worked can be enormous and the rate per hour overall diabolical. Would I count in the time sat here typing this up? If not - why - I wouldn't be doing it if I weren't in this business??
I will be interseted to see other peoples thoughts.
Steve