sactowndog
All-Star
You meant multiple substitutions. "Substituting in and out" does not infer multiple substitutions. Stealing extra rest is a luxury in comparison. The simplest answer is improving conditioning, and then 2ndly, trusting the bench. Every player in the league should be conditioned to play 48 min - as a professional.
I don’t think that is possible. Every game is structured for players to give maximum possible effort for x amount of time. That time varies but if a game requires you to go up and down something has to give.
For example water polo players are among the most well conditioned athletes in any team ball sport. But no way you can play a 2 meter player more than 4-5 minutes at a stretch without some substitute killing them on a counter attack.