I would say loans 20-21 age but stay with the club through their vital development and learning years. I remember fergie said something along the lines this when welbeck scored that first goal 17 years of age, it wasnt until a few seasons later he let him go out.
Good things happened when Sturridge went on loan to bolton and look how well Ngoo is doing up at Hearts! He wasnt really cutting it for me in the reserves and seemed in a rut, at times amazing but very in consistent. Fingers crossed he'll come back looking sharp preseason and goes on tour.
Cant imagin Shelvey accepting another loan, thinks he's better than he is atm. What about suso and sterling too?