Don’t think there’s an exact science to this when it comes to loan time leading to better development. I’m not averse to it, and I’m sure the rule of thumb would tend generally towards the more exposure and experience a player gets the better for them, but there are players who stay in the squad without going out on loan and it doesn’t hurt their development. In fact if they are in teams that have quality players they can get good mentor ship and learn from the people playing in their future position. See Phil Foden.
No need to rush anything, it’s a long season and we are in lots of comps- their time will come. We sent Nelson on loan and Eddie too, neither seemed to improve much from their time away from us for various reasons, but the latter is here and showing he’s a useful player when he gets a chance.