I've encountered only one L4 raid where there were enough other players to make a difference. For the rest, I've either been totally alone or had only 2 others, which still wasn't enough. It kills me to see a Tyranitar raid and no one to help me.
Niantic really needs to address this. They could expand the raid notice perimeter or (preferably) scale the time limit based on level and number of players. Like maybe on L4:
4+ gets 3 minutes
2-3 gets 5 minutes
Solo gets 7 minutes