Disposition Gain for Remaining Summoned?

Okay, new information. My maid was at 131 disposition, and rather than gain a point by having her summoned for 60 minutes, I lost a point and it went down to 130 instead.

New theory: Rather than a flat-out bonus, keeping a partner summoned is an action that slowly adds or subtracts favor points in order to return the maid's disposition to its initial value of 120 (which was pegged down to zero with their first summon).

Once again, I would like some help testing this out. I need someone with a partner below 120 disposition and someone with a partner above 120 disposition (I'll do it again if necessary, but it's a good idea to verify it with a different user and partner).

However, if possible, someone with a partner at exactly 120 would be ideal. If the partner at 120 were to remained summoned for 60 straight minutes and see no disposition increase or decrease, then that will confirm the theory by itself and eliminate the need for the other two partners to go through their tests more than once.

And someone else can do the TL;DR stuff. I have no idea how I can possibly make that shorter without taking out necessary details. >>;;