Pre-measuring components for darkroom solutions is very handy and effective. I use it for fixers, but that's all.

For developers, remember that you must keep the metol separate and dissolve it first. Metol forms an insoluble aduct with sulfite. That is solved in commercial developers by special coatings, but you can't do that at home. So preparing packets to mix up D-72 is quite practical, but you will need two packets. If you want an single packet, you might look to a phenidone based developer, which doesn't have this problem.