Generally speaking, it’s almost always a bad idea to fudge things to make it worse, but acceptable to fudge things to make it better.
If your players are rolling well, good for them! Sometimes players want to feel really lucky and like their investments paid off. If that makes your campaign too easy there are lots of ways to address it, and an easy fight will rarely if ever cause a campaign to crumble
But a series of bad rolls? That can absolutely melt a campaign. It can suck the soul out of a party and make things feel unfair or too difficult even when it’s just a string of bad luck. Preventing a TPK or allowing a PC to narrowly escape certain doom can be the difference between a player losing interest and them learning how to mitigate risk.
GMs should all spend some time reading up on the psychology of games and player behavior. Stress and frustration exist in the strangest, most illogical places because our brains are strange and illogical.















6e when?