as a level 40 player who does this aswell i can asure you xp for many of us is a priority goal now. Because what else is there? For me: i have the highest xp in my Instinct group. So being nr. 1 means i want to stay that way and the fastest xp right now is friendship leveling.
But… just this week we had network issues here where i lost my mobile internet for half a day, the half day i play. I missed an ultra friend level up of a teammate we set an appointment for. He had multiple levelups and would open my gift at 4 PM. He did. But i had no internet from at least 2PM until late in the evening. By 8PM i connected to the hotspot of my GF, logged in and instantly popped a lucky egg… 100k xp!
So if people really want to get their own double xp (and if you have enough lucky eggs) i would suggest just sending a gift before you stop playing, wait several (many) hours, log in, pop an egg and hope they opened.
if it worked, nice, if not then at least you got normal xp. otherwise you’ll get nothing.
The only other option is to wait them out and see who loses their patience first.