But I totally agree. I don't want "You have 5 days to defeat the goblin leaders. If you don't do it in 5 days, game over."
I have no idea why it would need to be "five days" on the other hand.
Kingmaker had THREE FUCKING MONTHS to complete the first main objective in the campaign (Beating the robber baron in control of the region). You had to be basically mentally impaired and deliberately lazy to miss the goal.
It also had an OPTIONAL but very juicy bonus reward for people who made it under a month. A month was still more than sufficient to explore every single map in the starting region and complete it at 100% with some rests to spare, if you knew what were doing and didn't abuse the rest mechanic.
That's an example of time limit implemented well and of SYSTEMIC, organic incentive to not abuse a convenient mechanic (rest) for your own sake.
P.S. It also tied very well with their weight/rest system, that actively encouraged a party to travel light since the benefit was greater than carrying tons of trash loot and going at a snail pace.
