It has worked out in the short-term; it can also be the ruin of a player. Further to that, we'll see what the genuine fallout is through the remainder of 2020 and into 2021. He may have a Lampard/Charlton/C.Ronaldo etc. Constitution far beyond what normal types can endure, he may not.Of course it is dangerous, but we would have not qualified to the CL without him. Not only did he score and assist many times, but he also converted 100% of the penalties - and we (Man Utd fans) know better than very many others, what it is to miss penalties.
Under Ole’a system, we somehow manage to win many penalties, and the skill of converting them is valuable per se, very valuable.
The reasons why we kept playing him are obvious, but it's something that should never happen again at a club with the resources we have.