In order for players on loan to benefit from the +1 endurance event, their loan spells must end by the start of Day 1.

That’s the case when you loan him out for two seasons 😄
But in theory, yes – even if, for example, we loan him out on matchday 2 or 3, the loan would need to last until the end of the season so he can return for the new season and benefit from the stamina point
That’ll prevent abuse, and loans will be just like before – beneficial for both clubs!

So yes, you’ll have to manage your squad so that all the players on loan come back, but you can’t have it all 🙂