I work at a campus law enforcement agency — we have a pretty strict budget when it comes to practice rounds.
I’ve found that by doing dry-fire exercises — as well as practicing your fundamentals: breathing, trigger squeeze, sight alignment, — you can keep sharp in your marksmanship.
Granted, nothing is better than sending rounds downrange, but I actually improved on my yearly qualification by conducting these exercises on a weekly basis.
Just because you don't have time — or the rounds — to practice is not an excuse.
When it’s the real deal you don’t want to be counting on luck to stop a threat.