What? Why?
How many weapons are handed out with an upgrade is determined by balance only.
Weapon would be re-balanced according to number
...Gren G43 upgrade to focus on close-mid range firepower with 3x G43, but with toned down moving DPS to avoid blobbing...
the total DPs of the squad is balance issue the number of different weapons is design.
If they need 2, 3 or 4 G43 is not a question of consistency, especially not if it is communicated to the players.
Comminication is also a reason to avoid 75% of weapons replacement. It would be better if some standard was used for normal weapons (not lmg/AT) like half the weapons or all, in this case 2 or 4.