Sorry, this is a bit intense (no pun intended)
It's surprising to see coaches still programming intensities off 1-3 rep max (RM) and percent body weight in the first few weeks of training. Imagine the following scenario: 25 track and field athletes walk into your weight room for the first lift of the year. You have two ways to approach the situation. First, you do a "intro" block lasting 1-3 weeks so the athletes can learn the movements you want to test. After said movements are learned, you test a 1-3 rep max. On the other side, you can use percent body weight and avoid doing max testing so the athlete knows a target weight they should be hitting. Either way, you will most likely lose. Good luck telling the 130lb freshmen sprinter to lift this pre-determined percentage of her body weight for 5 reps in the Front Squat. Mind you, she has no lifting experience and will most likely get crushed. About 80% of the time, the weights on your lifting card or in your phone are typically wrong and will most likely need to be adjusted. So, why don't we just make it easy and start with a blank slate? All you need to do is record the weight you do from session to session. That way, you can see what you did last time and use it as a reference to help determine what you should do next. If the 260lb discus thrower can't Dead Lift the weights on his card with good technique, he should put down the weight he actually did with good technique. Then, in his next Dead Lifting session, he will attempt to beat said weight. Now imagine the professional Baseball athlete with a ton of training experience showing up to a team lift. He sees the numbers on his lifting card are too low and determines this session will not be a challenge. What do you think he is going to do? You guessed it. GO UP IN WEIGHT! By avoiding pre -programming intensities in the early stages of training, it helps the athlete select their given training age and in turn, makes your program more sensible and specific. Once the coach gets a better understanding of each athletes strength level, using percent body weight to program intensity is a great way to help guide athletes and keep them accountable.