Olivier Giroud might be the best one touch finisher I've ever seen. He was incredible at it, possibly because he had a lack of pace causing him to have to get his shots away early.
Yes, he is very good in that respect. Van Persie, Van Nistelrooy and Solskjær were greats at this at United in my time. Frank Lampard and Raul come to mind.
Statistically, I believe Van Gaal was on dry land, as for most players, hitting it first time reduces precision enormously. Unless you practice enormously, you need space and perfect lay up (Rashfords goal vs Wolves) or being so close to goal as to not need much precision (Højlund’s and McTominay’s goals vs Wolves). If you keep the ball until a player gets time to cushion and fire, he can do that from all around or even outside the box with the increased precision it allows for. Normally, first time shots are wasted opportunities. However, at the highest level, the best defending teams will not allow the time to cushion and shoot even outside the box.
Solskjær’s way around it as a player, was countless hours practicing first time shots with car tyres as goals. He always shot before the keeper expected, and first time shots give increased power often, exploiting the ball’s incoming speed. As a coach, he has been ridiculed for his ‘shoot, shoot’ rehearsal, but it is in fact a concrete exercise he would use with top players to overcode the Van Gaal or Wenger schools of controlling the ball to much that was imprinted in their systems from earlier coaches. Bruno, Martial, Rashford scored many first time or early taken shots in his time. Counter attacking also gives the space needed in shooting situations to exploit that.
Guardiola’s way around it is systematization, lots of preprogrammed running and passing patterns to give shooting opportunities with some space and closeness to goal even against very good defences. His weakness, as we know, has been against the very best defensively focussed teams, like Solskjær’s own, who manage to minimize that space close to goal.
So I’d say the opening question depends alot on what the opponents allow for, and how much training hours you are prepared to allocate to that particular type of finishing or setting up moves.