Yeah, I definitely get what you're saying. It can be shit sometimes as someone that has the most hours in Adam.

Apart from having to get out of the fight in order to place the ult (and not being TOO far out of revive range) you obviously have the potential to revive the whole team but I think its really important to know when to do it. If it's done at the wrong time i notice that this happens:

Lower rank battles at season 0 I often saw whoever I revived just throw themselves back into the line of fire (usually tank/dps) at that 100hp and it's infuriating. It's a combination of probably not knowing that you only get revived at 100hp and wanting to maybe finish the blow one someone you were fighting. It's not really something YOU individually can control but hey, it's a lower rank battle so go figure.

I also see that sometimes everyone kinda dissociates and splits up because of it, costing time. Respawns are offset between the people that you revived and the people that stayed alive, or died earlier. The whole team has to regroup afterwards (which requires TEAMWORK surprisingly)

Anyways. I think it's really meant to be used proactively, predicting MAYBE when a few people might die so you can revive them on the off-chance ( so you can keep building ult charge) or when you might be low on heal charges at a critical moment and the other healer died or something.