Wartime tends to show that the combat forces of peacetime tended to lack certain preparations. More specialised forces (NOT quite our "special forces") appear and vehicles appear and more countermeasures are introduced.* They aren't necessarily available when useful, but to be available sometimes is better than never.
This is a recurring pattern, and to take it into account may enable one to guess where we are lacking today.
Let's look at something that everyone seems to have an opinion on already; a tank platoon.
Today the MBTs of a tank platoon are meant to be identical and deviations from this are - safe for markers - rather technical imperfections due to different production batches, poorly functioning components, different state of being worn out and so on.
Would we still want tank platoons of identical MBTs after a year or two of experience-gathering in intense land warfare? I suppose no.
We might prefer upgrade kits (integration by army workshops) like this:
(1) command & control kit (longer range radio, larger and higher resolution computer screen, laser target designator for PGM fire support)
(2) air threat kit (LINK 16 download of air threat picture, Rheinmetall FIRST IR-based alerter device, radar warning receiver, maybe remotely-controlled weapon station with 20 mm gun that's usable against drones)
(3) acoustic warning kit (sniper detection, mortar & artillery triangulation through radio network, infrasound direction finding to helicopters)
(4) mineclearing kit (KMT-like)
(5) recovery set (winch, dozer blade - also useful against barricades and surface-laid mines and to create hull down positions)
Most modern tank platoon organisations only include four MBTs, so having so many different sets would specialise every tank (and the mineclearing set would be carried rarely). The loss of any such specialised tank might be compensated by other tanks with the same set in another platoon of the company, but not inside the platoon. Then again, having but one such kit in the platoon would often be better than having none. Today we have none.
*: Look at a German WW2 fighter, for example; the Bf 109E-1 series was the latest design as WW2 broke out in Europe. One light and one heavy fighter type. The light fighter evolved into fighter-bomber, bomber destroyer, night fighter, fighter reconnaissance, high altitude fighter versions in addition to successive baseline versions.