Don't have absolute number of days on the progress. Pretty much like how the gym level status bar.
Raid together, hoot gym or trade is quite straightforward both will gain a day. But exchange gift if one accept but the other didn't, will both get 1 point for that day?
I can imagine those with multiple accounts having this daily burden to exchange gift, raid, spin and catch daily. And after doing all that also can't really trade for $ which I think most of the uncle or auntie are probably trying to so by multi accounting.
I think most will stop multi account soon since not much incentive anyway.