Comment by rheeseyb

That's absolutely true for sure, and I'd go so far as to argue that it's one of (if not the) primary driving forces behind development tooling decisions. Whereas some changes are well suited to e.g. unit testing (and where a passing suite of tests provides that instant feedback), when working on the design or interactions of an interface it's very important to actually "see" and/or play with the result of each minor tweak, so the faster you can make that loop the more pleasurable the development experience will be.