Ah. Well, if that's part of the competition rules, then so be it.
In Australia, what you call 'rolling subs' is called 'unlimited interchange'. 'Rolling subs' is what we call 'anytime' subs (ie while play is continuing), usually left for preseason matches, really young matches or some other friendly format.
I use 'rolling subs' in the UK context when I discuss it on here.
Personally, I think a few refs on here have a bit of a bee in their bonnet over this. We're there for the players - so if that means that they're using a permitted modification for their benefit that that's more important than our sense of what's 'right proper football'. Can rolling substitutions cause problems? Well, define 'problem'. Teams may often fail to follow correct procedure and do it not from halfway, or have the player come on first. The extent of the 'problem' I've ever seen that cause is a very half hearted whinge from a player on the team doing the right thing - and it's a very, very easy problem to deal with.
I pity those of you whose local association has, for whatever reason, deemed it a requirement for the official to attend each substitution. In rolling subs, that's just ridiculous and completely unnecessary. It's a waste of everybody's time, tires the ref out and makes the referee look like a pedantic, overly officious twit. Even with NAR's we don't expect the AR to attend each change - for the same reasons. I would if I was relatively close, but that's about it.
Actually, I'll stand corrected. Yes, sometimes you'll get teams that are annoying, especially a junior coach who wants to make 30 subs a game. But that's also somewhat expected at that level, and there are ways to manage that too (substitutions on consecutive stoppages are really irritating). For the most part, those levels will expect a lot of changes, so no big deal. And when it's, say O/35 the players will generally all be grateful for it! The only other issue is when it's done right at the end of a half. As a result, every referee I know becomes extremely deaf in the final minute of each half. In the extreme rarity is when a team will try to call for them to interrupt a quick throw. Again, selective deafness fixes that. The time consumed can be an issue, so with rolling subs most referees don't want for the sub to get into position - they'll pretty much blow the whistle as soon as he's on the field. Most coaches are smart enough to be aware of this. Sometimes you'll get an argument when it was a defender not yet in position and the other team gets a good attack/goal.
But let's not pretend that limited substitutions aren't without problems either. It can place big demands on unfit players, it creates more paperwork for the referee, and can easily result in teams being 'punished' when they've used all their substitutions but then a player gets injured, particularly as the result of a foul (or, on the other hand, rolling subs allows a temporarily injured player to be immediately replaced, which I think is a good thing) Not to mention the issue around extra time.
But that's perhaps part of the point; that it's a tactical decision. But in lower levels perhaps there's no need for that sort of tactical restriction, so it's good to just let the guys play in whatever manner suits them.