It's up to you really. You never have to push for PR's if you don't feel like it, but it's encouraged when you're feeling good.
Just keep in mind that it's advised to leave a rep or two in the tank, so not complete failure, but more like technical failure if that makes sense.
In BBB you can still feel free to push the PR's, although sometimes people experience a slight decrease in strength performance due to the increased volume from the BBB sets.
Really it all just depends on how you feel, and how accurate your TM's are.
Remember that the TM is just a tool.
All the best