I was playing Ana a few times the past few days and I generally do a decent job at keeping people I can see topped up, but I'm awful with hitting the sleep dart (tho I landed a few clutch ones before), and nobody eeeeeeever coordinates with me.
I tell the Genji I have my ult, he has his ult, Genji runs away and swords someone on the other side of the map.
I tell the tank I have my ult, they have their ult, they run away and don't let me boost them to push.
Seriously, the only people I reliably can nanoboost are D.Vas or Hanzos. Everyone else just runs away from me.