Head installation question

The one thing I never liked about installing everything already assembled is the possibility of a lifter not bleeding down fast enough and bending a pushrod or pushing the valve retainer into the stem seal.
It just seems so much safer for it to go on head first, then rockers and pushrods, and even then it's a good idea to tighten them down slowly and evenly just in case there is some problem (like a rod not being seated correctly)