I think the risk of injury is higher whend you train them above 80%.
In the last 3 seasons in my 3 teams, i had only 6 or 7 injured players in total by only training with condition above 80%.
Thats about 1 player season, team.
I still have a few during matchs.
On the first season my average was much higher because i keep train until the % i whanted.