4 is an overkill , SAF had that because he played 2 strikers upfront.
We just need one fit striker. I don't consider Martial as a starter.
I appreciate that SAF played two out and out strikers, but arguably Gakpo, Moukoko and Martial could all play as the number 10 or as a wide striker alongside Sesko, and Martial is only fit for 50% of a season.
However, the main difference between 99 and now is the number of substitutes allowed. Strikers are the most substituted position, when a team is chasing a game, the manager will either switch things up front, or throw on an extra striker.
In the FA Cup Final of 99, top scorer Yorke was rested for the Champions League Final, Keane went off injured early on and Sheringham was brought on alongside Cole, with Solskjaer moved to the wing. Sheringham scored the opening goal, and had a hand in the other.
A few days later in the Champions League Final, Yorke and Cole started, Sheringham replaced the winger Blomqvist, and Solskjaer replaced Cole. Once again, Sheringham scored United's opener, and then set up the second, scored by Solskjaer.
A successful team needs lots of options they can rely on, to cover injuries, suspensions, loss of form, too many games, change in tactics, and just generally to freshen things up. The league game against Villa is a classic example of how we missed a few players from the starting XI, and we looked awful.
In my opinion, our ideal squad would have 3 keepers, 8 defenders, 6 midfielders 4 wingers and 4 strikers (25 in total), plus a few kids. At the moment, I think ETH has about 12-13 players he trusts.