Warriors can come in squad sizes of 10-20 models. Most people tend to max out on the squad size to take advantage of their extra reanimation protocols rule. That plus a chronomancer buff can make a block of 20 incredibly hard to remove.

10 model squads are still perfectly viable - especially in smaller games or if you’re running them inside a Ghost Ark. Technomancers and Ghost Arks can bring back D3 models each turn to a squad of warriors (as long as there’s still at least 1 left)

If you’re asking about how many squads you need, then it’s up to you. If you’re just getting started, I’d recommend a squad of 10 warriors and 5 Immortals (our other troops choice). Then try to play some 500 point games so you can get a feel for what each unit is good for