Pre-emptive rescheduling of workouts might make sense if something outside your control like work or family is adversely affecting recovery and thus performance in the gym, but most have settled into a routine by this point in their training, and this option isn't even possible for many.
If you are gassed beyond belief after completing your first set of 5 for the day, it makes sense to drop the weight a bit and keep going for two more backoff 5s.
If you actually cannot make all 5 reps, then it makes sense to move on to 3x3.
I think an adv novice (i.e. HLH) 1/2/1 sched and 3x5 with backoffs would be fine for a while. 3x3 on an adv novice 1/2/1 doesn't seem like enough volume and I wonder if riding out the gains is worth screwing with the workout schedule. Something like a heavy 3 and then 2x5 backoffs on the normal schedule sounds like something that would work for me.