Every 4 days for pink swayers ends up being basically one viable attempt in the fertile window without them having to track or monitor anything.
Every 4 days for blue swayers is in addition to 3 attempts in fertile window. This is for (as I just explained right above this) regular exposure to your husband's semen and also for benefits for him by improving sperm count and quality. And then in addition to that you have the 3 attempts. (and I didn't go into this above but some guys who do have trouble completing the transaction if they tried to do it 3 times in a row, could actually sneak in another viable attempt this way for example if it fell on O-2, and then he could not DTD the next day or the next morning - it's like a back up plan too for guys who cannot always perform under pressure or many times in a row.)
Remember, these patters are just tools to accomplish things we are actually trying to achieve here. The important thing seems to be one attempt for pink, and more sperm on hand both coming out of DH, and also on hand to meet egg for blue. Both can be accomplished with e4d in different scenarios.