My pre-planned range days are solid events booked in advance. These are typically handgun only affairs and run from 4 to 7 hours in length and I typically burn through 600-900 rounds of center fire ammo and 250-600 rds of rimfire ammo, though the rimfire has been attenuated since it became scarce. A normal one of these range days will have me running ammo through 5 to 8 handguns.
There are some trips where something goes wrong with a gun. Rarely is it a genuine mechanical failure of some manner, but that has happened on occasion. More often, it'll be some new smallish pitfall with a particular handload that is still in the stage of being vetted before I go in to full production and earmark as a "pet load."
Sometimes, I'm just shooting craptastically.
Often, I will have a particular handgun or gun/ammo combination in tow that I can lean on like a ROCK, something that always comes through. Shooting well with it can diffuse a lot of the stress of a lousy day that seems to be unfolding. Having a "ringer" along is always a fine idea, even if you don't end up shooting it.
Also, I keep a strict bunch of notes in my log so I know everything I need to know about each gun, so I have everything in order when I'm staring down some "issue" and how to overcome that issue. Some guns come along on a range day
specifically with the intent to have a "rebound" and an opportunity to get back in to my good graces.
I've had a bad range day before, or simply a bad day for
that particular handgun. It's a downer, but I try to look at it as a challenge to overcome. Most times, I do exactly that. Sometimes I fail at it repeatedly and that gun has to go away.
But it's good to have some kind of a plan in place.