I forgot to add this to my other comment. Yes, a multiplier works wonders. (I typically added 30% to my own estimates, which covers all the little incidentals that trip you up, and coffee breaks).
I've not been forced to work longer than an 8hr day since the 90's.
I thought your comment stating that time should be added for both research & design was actually a reasonable explanation for why I need the *3 multiplier!
