I see where you are coming from. However, our depth is laughable. The team is playing better but it hasn't done so over a season. For that you need depth. Also Ole needs to make his mark on the team. He is currently adapting to the team to play how he wants but it is not 100%. I believe we need 5 signings minimum.
I'm not sure the depth in your squad is laughable.
GK - DDG, Romero and Grant so fully covered
RB - Dalot, Young, Valencia, Darmian - Valencia and Young are old yes, but for one more season they'll be fine as back up. I'd suggest losing either Valencia or Darmian
LB - Shaw, Young, Rojo - could do with a bit more depth here!
CB - Lindelof, Bailly, Jones, Smalling, Rojo - so a decent signing here would be useful.
CM - Pogba, Herrera, Matic, McT, Pereira, Fred - also Mata and Lingard can slot in here depending on formation
RW - Lingard, Mata, Lukaku and anyone else they randomly slot into this position - You need a specialist here
LW Martial, Rashford, Sanchez
ST - Rashford, Lukaku
Remember you've also got Mason Greenwood coming through at ST, Chong at RW, Tuanzabe at CD, also Gomes, Garner and plenty of others, they wont all make the grade, but they make for very decent back up. I think on paper with a couple of signings in the summer you have a very strong squad. It's just one that has been under estimated under Mou and the majority of players are finding their form again right now. So talk of 5-6 transfers in the summer is probably not needed, maybe over 3 transfer windows that'll work but I wouldn't do it all at once for risk of upsetting the balance and team spirit you've onlly just won back after many long and tedious years!