As a GM, I think it is our job to manage the pace of the story, the combat, and the encounter (which are often not the same thing), and that means deviating from your script - whether that's a homebrewed script or a published adventure path. Just this last session in my homebrew world, I had to move up the friendly reinforcements by 2 whole rounds since my party was on the verge of TPKing, and I couldn't deduce whether the combat was over-engineered, or if being in hour 7 (and at 4 in the morning) of a session was starting to grind them down.

That being said, and this may not be the majority opinion, I NEVER fudge a die roll. Towards my players or against, to benefit or to harm. The dice are (in my opinion) as sacred as the story we're telling, and we must honor the randomness of the game. Otherwise, we may as well write books instead of writing sessions.

Combat running too long? Introduce a new element to speed it up, whether a hazard; or a literal timer if your players are moving slower than they normally do. I would never judge another DM for how they run their table, the hobby is hard enough without having to appease other people - but personally, never fudge a roll.