Personally, I think it's a huge deal. Imagine having an army and training against each other, all behind closed doors. Your opponent wouldn't know what you're cooking up, and that's gotta be terrifying. It's the same thing here. The main squad doesn't even need to scrim other teams as much, because they have the reserve team to use as a 'punching bag' they dont need to show anything. This lets them focus on theory-crafting, limit-testing, and really going all out, without leaking strats in external scrims, in scrims you have to tip toe around as to not show your full capabilities, And let's be real, most scrims are fake and useless since no team wants to show their full potential; just like your they don't want to.They have the freedom for that, while other teams do not.
But here's the real deal: the reserve team can mimic certain play styles of opponents, which is pure gold for the main team. They get to understand how to counter those styles and even pick up on some hidden intricacies.
In my eyes, this is such an underrated tactic that literally NO top team is doing. This is how you build generational success. You stay ahead of the curve, you predict the meta, you keep evolving. When teams fall off the map in CSGO or Valorant, it's usually not because their mechanics went sour. No, it's because another team cracked their code, not their aim or niche set plays. And that's why you NEED a reserve team—to avoid the stagnation that sinks so many other squads.