That's a valid mode of play, but I feel like if we're going to have agreed upon rules we should follow them, and not unilaterally change them. If the rules say "you spot the trap on a roll of 10 or above", the GM deciding you just don't spot it because they say so can feel wrong. It can feel like cheating. We had an agreement, and they just broke it.
On the other hand, if in your session 0 you all agree that the GM may fudge things for more drama, then have at it.
On the third hand, I've done things like "the rules say X but I think that's going to stink here. Anyone object to changing it?".
The important thing is everyone gives informed consent.