Is it safe to close the lid while an app (Xcode) is updating - during "installing" phase?
Solution 1:
Yes, it is perfectly safe to close the lid during updating of Xcode. The update process will of course pause, but resumes automatically when you open the lid again later.
I don't think a method exists to make the update timing of Xcode more predictable or interactive. The progress indication they share is all we get, and it may sometimes be off by a lot.
Delete-and-clean-install seems to work quicker for me in some cases at least. However, I haven't experienced any negatives coming from updating Xcode in place (except the wait while updating).