I'd only start getting worried about KWP's development if he reaches the ages of 24 and 25 and is still not getting proper game-time.
But that won't happen. So I have zero worries. He's a good player. Doubt he'll ever be elite or Englands number one right back but he'll either save us a bit of money by providing us great depth, happy to be in the squad and being our own or he'll make us a bit of money for not being good enough.
At 24 or 25 and not playing reasonably regularly (lets say minimum of 10 games a season) and no chance he could make it at Spurs or probably any PL club - so a waste of everyone's time.
Spurs need homegrown and club trained players - one of the reasons we are running into problems this season is our fatigued players getting little rest and we have too many overseas trained players so can only buy home grown to relieve the pressure.
So I'd much rather try KWP out a few times (lets say 5-10 times with meaningful minutes) this season and assuming he passes that test, more playing time next season than this season. And if he fails the audition, we need to move onto other youngsters.