IBuild148,
It varies. If I am building german tool clasps, then I will build them all up production line style. Then I will move onto something else for a bit. Those buggers are small in 1/35 (the armor scale I work in), I cannot fathom how cross eyed I would be building those in 1/48. If I have assemblies that are interconnected in one form or another then, I will go "all out" and build it all up.
Directions, unfortunately, are not always clear. The things I do to get through those, I-am-going-to-launch-this-(insert favorite explitive here)-thing-across-the-room moments, are: hold the part up to the instructions (i know it sounds simple, but it does work); references, be they book, online, whatever; sometimes it comes down to using your own common sense (i.e. how would I build it given the technologies of the time, how accessable is it/does it need to be).
If you are getting frustrated with the assembly, set it aside and come back to it latter. Sometimes that approach doesn't work and it is a matter of male pride. The testosterone levels spike, the mono brow comes out, knuckles errupt with hair and start dragging. Then come H-E-double hockey sticks or high water you will finish it no matter what.
PE can add some incredible detail to your kits but, sometimes you will have to ask your self: Just because the part is on the fret, do I really need to use PE? Would the styrene part work just as well? That is up to only you
Sorry for the long windedness. That am cup of java has kicked in.
Cheers
Dave