I usually have 1-2 starters who are lower vs left handed pitching. I start them on the bench against lefty SPs from the beginning of the season. They almost always are still at 100% at the end of the season. The other 6-7 I rest early in the season but only 1 at a time so I stay close to full strength. By game 130 all of those 6-7 have had 10-20 games starting on the bench depending on their durability. That means all of my starters are at 100% for the final 32 games when other teams have several starters dipping under 100%. This keeps everyone at 100% the entire season but does take a little more "hands on" time to manage..