I use S&R full strength when I am planning to follow it up with a polish and wheel sealant. With fresh wheel sealant applied, I only need to use regular car wash soap to clean the wheels. When the sealant starts to show some wear (around 3 months for me), I may use a 1:1 S&R:water mix to do some light cleaning until I have time to do a full round of polishing & sealing again.
For the APC, I keep 4 different dilutions on hand (full strength, 1:1, 1:15, 1:30).