When do you think it is fair to revert?

[Aeroboi]

I never really role play and I'm mostly building stuff.

To build stuff you test, to do so you use "cheat menu", "hyperedit" and a plethora of flight reverts, quiksaves and quikloads.
If I were to play career and use revert flight in any case it would be stupid. Still I like things to work out properly and have the tendency to use this option. I don't want to make due with a dead Kerbal just because I forgot to drag a radial engines to the first stage just to see my rocket tumble into the ground just because I forgot to click a specific setting in the context menus when inside the editor.

Or do all of you people build rockets out of the ground 100% functional without quirks or issues and accept every mistake you made that leads to failure?
I mostly always make my rockets 100% functional from the get go, but sometimes I forget something and often that mistake is critical. It's not like a real space program would forget to light all corresponding first stage engines.
While in a real space program anyone would verify and check each step is done properly. So if I were to forget putting any engine to the correct stage and I would fail my launch and kill my crew then it wouldn't be a real space program would it? Is logical, makes sense?

Edited March 31, 2019 by Aeroboi

[goldenpeach]

I mostly revert when Jeb,Bill,Bob or Val dies in a crash or when I'm not patient enough to wait for the crash - in example, when I realize my probe won't even reach space and I'll have to spend some time doing nothing but watch as my probe either burn up or crash.

[N_Danger]

 When ever a mission fails totally. If I think I can get partial Science and Kerbals can get back alive I roll with it.

I will quick save if there is a high risk of death.

[Geonovast]

Always.

I tried a no-revert game once.  I got sick of losing progress from loading backups due to the sheer number of stupid bugs that affect you early in the game, like a plane doing backflips on gentle landings because the landing gear are so hilarious borked that the small ones aren't even worth trying to use.

 

Of course, now I revert all the time.  Most of my time playing is mainly just seeing if a design will work... which is a lot of "testing"/reverting.  Once the design works... I make something else.  Hopefully the bug will bite again soon and I'll actually be able to really play the game again.

[Fraston]

Any time, silly. Cheating and reverting is what makes the game fun for me because I have legitimately tried to make orbit of the mun more than half a dozen times, each of which failed. I can land a tin can with almost no propulsion and minimal fuel from orbit on any low-gravity body, but I am absolute bullcrap at changing SOI’s. I cheat most of my craft into orbit because I know I can get to orbit of Kerbn easily with the right launcher,  and it saves me the trouble of flying each one into orbit. I revert any time I kill one of the original 4, because, well, because very understandable reasons!