Different progression strategies
I've actually found that RPE helped me minimize my inter-set rest times as well. If the RPE is increasing every set, I'm not resting enough. I've found that I could reduce my rest times closer to 2-3 min when doing upper body or RPE 7 sets. But need closer to 4min for RPE 8. I haven't been prescribed higher RPE yet, so not sure about that.
One other thing I'll mention is regarding the workup to a specified RPE. I personally target a specific weight based on previous sessions performance. Depending on how the weight comes out for RPE on the first work set, I will adjust it if needed. I haven't been able to gauge the right weight from just warmups, but maybe that comes with more experience. After all, I've only been using RPE for the last few months.