I think that entirely depends on the individual, and perhaps more so the program you're on.
a lot of the (more successful) training programs out there have progression and percentages laid out for you, so really you just have to stick to it as best as possible. classic examples like Juggernaut training, 5/3/1 etc. More recent examples like CT's 915 program.
If you're more the type of trainee that just likes to keep pushing the weights and work harder each session (like me) then just judge how you feel. CT's more recent articles reference this idea in 2 ways -firstly stick to work in the 80-90% range, this allows for pretty intense, heavy sessions without burning out, then you can retest your max as needed, maybe once a month or every 6 weeks depending on how YOU feel. The second way which is how I like to do it is to stick at the same weight for a couple sessions but just try and own it (focus on rep QUALITY rather than the weight lifted), so maybe 100kg bench for 3 reps is a tough effort on the first session, the next session it feels easier, less grinding, third session you might even go for 4 reps... then increase the weight next session. See CT's Russian Strength article, or just google double progression.
Of course if you start to stall then it's a whole different ball game, try to reduce accessory work initially, maybe look to deload if that doesn't help.
Hope thats kinda useful!