Freeplay/Parlay/Diminishing Returns?

To put it short how many teams should you put on a freeplay on -110 before each additional team will lower your expected value. I am guessing somewhere around the 5th one.

Does the book offer fair parlay odds or that "parlay chart?" If they offer fair parlay odds, there's no set answer to when your EV diminishes.

Besides just the EV, how much variance are you willing to tolerate? Even if the EV of a 4 teamer is higher than a 3 teamer, are you willing to only win 1 out of 16 times rather than 1 in 8? Much more likely with bigger parlays to get nothing out of it.

Just something to keep in mind.