You're arguing gibberish.
If your argument is that we need to be three-deep at every position, I would classify that alleged need to be pure fantasy. I'll take two-deep at every position first before going for three-deep. And given the financial condition of the club -- not to mention PSR -- we're in no position to be thinking about being three-deep at every position.
But if your argument is that we need to be three-deep only at the LW position I can respect that argument, but my counter -- which is unrefuted -- is that we need to be sure we're two-deep at every position first before we can start thinking about being three-deep.
My argument is neither. Your premise rests on a flawed assumption which pigeon holes Dorgu and Cunha as
only left wingers. But they’re not. They’ve both been used out there because we don’t have a proper left winger, but they’ve also been used elsewhere. Indeed, Cunha is most at home roaming away from the left wing into more central areas. He pops up all over the pitch, which means when he plays there we’re often left without any proper width on that flank. They are both players who are somewhat versatile and can feature in various roles.
The only position(s) we can confidently state that we're sufficiently deep in is CB -- De Ligt, Martinez, Maguire, Yoro and Heaven. There are doubts about some of those names (injuries, contracts, etc.) but all we know is what we know now, which is that really don't need to think about deepening our roster of CBs unless 1 or 2 of those names are no longer with United next season.
I suppose we could also argue that we're deep enough at keeper, but doubts about Bayandir are not unreasonable. And surely this has to be it for Heaton although maybe we can keep him for one more season as our third choice keeper. Let's just assume that we have no summer transfer business on the keeper front.
Everywhere else throughout the squad we're just way too thin. We need two fullbacks, either to upgrade on Shaw and Dalot or to be their cover. We've talked about central midfield -- at least two and probably three, depending on what becomes of Ugarte. I assume Bruno will remain and if he does we don't have a great option behind him other than Mount (but Mount is a significant downgrade from Bruno, but I don't see anyone taking Mount off our books next season). Before we get to the wingers, who have been very good for us this season, let's talk about the need for cover at striker. Zirkzee has something about him, but he's just not a goal scorer and the very point you have made about a long season applies to the striker position, which I don't think anywhere here would argue we're amply covered at. That's a genuine priority, slightly less so than central midfielders and fullbacks but still a priority.
And then we have the wingers. At this point it comes down to opinions and you clearly believe that Cunha and Dorgu just aren't good enough -- thus, the argument to buy another LW -- and that we shouldn't given any serious thought to Lacey or Gabriel -- making it four options at LW.
Again, straw men. Why do your arguments always seem to rest on misrepresenting other people’s arguments with hyperbolic nonsense? I think Dorgu and Cunha are both good enough to play for us. In one of my recent replies to you I described Dorgu as “incredibly important” so why are you trying now claim I don’t think he’s good enough? It’s dishonest. If you were able to argue the points on their merits you wouldn’t need to engage in such cheap tactics.
I made a different point - that I don’t think either of them are nailed on as automatic starters in that one particular position in every game we play in a busy PL/CL season. The best squads have options, and a common complaint in recent games is that we’ve lacked genuine width and threat on the left flank, which is likely why the club is reportedly targeting a let winger. And I have no idea why you're listing Lacey as a left winger - his best position is on the RW coming on to his favoured left foot, and that's where he's featured so far for the first team. Again - another example of you trying to twist things to fit a particular narrative.
Currently we ostensibly have eight senior attacking players for four attacking positions: Mbeumo, Amad, Bruno, Cunha, Dorgu, Zirkzee, Sesko, Mount (when he’s fit). And within that there’s a fair amount of flexibility and interchanging, with some of those players featuring in various positions.
That hasn’t been enough for our lightest game schedule ever, so it’s certainly not going to cut it when we’re playing 2/3 tough games a week. Assuming we sell Zirkzee (which we should), there’s plenty of minutes to go around for everyone, including a new LW and/or CF if we bring them in, and including youth players who might come through.
There’s a reasonable argument to be made over whether a back up striker or a LW should be the bigger priority. That will likely depend on who our manager is and what system we play. I could be disingenuous and say that we don't need one because we already have four options for striker - Sesko, Mbeumo, Cunha, and Chido - but I’ll leave such narrative driven accounting tricks to you.
I’ve repeatedly said that I hope Lacey and Gabriel get first team minutes. How is that not giving serious thought to them? But JJ is still only 15 FFS, and players that age go through all sorts of ups and downs, especially when trying to break into the senior game. Shaping transfer policy around what a child might do in the coming years when you might be in the CL next season is incredibly naive. If he makes the step up in the next year or two he’ll get opportunities.
So be it. Your opinion is just as valid as my opinion that Cunha and Dorgu have established themselves as great options at LW. As for Lacey and Gabriel, I have no idea what the future holds for them and your speculation about their future roles at Old Trafford is just as valid as mine.
Given that you haven’t even managed to get JJ’s age, or Lacey’s position right, any speculation from you regarding their prospects seems to be built on sand.