There's a big leap between truing wheels and building a bike from scratch, but I went ahead and checked it because I probably could. I can't press in a headset and I can't chase a bottom bracket. Mostly, because I don't have the tools (and they're too expensive to amortize against the number of bikes we build).
I still let experts take on some of the job just to get the absolute best touch. A very experienced mechanic can do it so fast and so much better, but then I love the feeling of having built it up myself (or a team effort with my sweetie).
Frends know gud humors when dey is hear it. ~ Da Crockydiles of ZZE.