Individualization all starts with the concept of adapting and fitting the program to the athlete to address their strength and weaknesses relative to the sport being trained for.
Too often it is the opposite, one size fits all with the athlete being forced to conform to a system of training that is contrary to their needs. The argument for this especially in team sports where there are large squads training is that there are too many to individualize. This is not the case. It takes a lot of work and organizational skills. I learned this many years ago as a classroom teacher with a wide range of students that the answer was to group. In training for sports, I assign groups that are color coded. Each athlete can be assigned a specific color has a different training load or exercise emphasis. This enables athlete to adjust the training emphasis.