After beginning testing for our baseball off-season with a rep max calculator, and not a true 1RM I was completely surprised what you can get from that information. It has added to my reasoning of why we don't need a 1RM, and why it is beneficial to us to utilize a multi-rep system on almost all lifts.
Understanding of RPE
In order to maximize our time and ability in the weight room I have moved to a rep-max calculator instead of a 1RM for most lifts. This has proven to me to be extremely advantageous for most kids, and has shown a ton of growth in our weight room environment.
Compared to 1RM testing a rep max can provide an accurate enough conversion for our weight lifting off-season, while not stressing the athlete with heavy weight multiple times.
With the amount of athletes in an off-season program and limited time on a high school schedule I will need to test a large amount of athletes in a short time frame.
Understanding of RPE
Although I do get to an RPE scale, it is only after they have been in the weight room for some time and developed an understanding of their own personal perceived exertion. Until then we use maxes and percentages to measure where they need to be.
When testing for a 1RM I think we tend to lose sight of the sport we are coaching. I am coaching baseball players, and not power lifters. I need repeat performance of high level work on a consistent basis. In order to compete the entire season I prefer to focus on building strength with a capacity to use that strength over and over again. This is a way to build that into their mind when they ask "Why don't we 1RM" I get to build more confidence in quality reps at a high level of strength rather than 1 rep.
Although I use rep-max conversion for most lifts I do have a couple of exceptions. We no longer use it for dead-lift, and I do not plan on using it for hang clean. These lifts are too intense with too much weight to try to get more than 2 reps at a time out of them. I tend to see form break down past 2-3 reps, which then defeats the purpose of the lift.