Lanefan
Victoria Rules
It's a problem for the DM as well if-when she's trying to run a published module built around a premise like this (and IMO far too many are); yet the PCs just won't stay on schedule. They're either early, which is good for them but bad for running the big set-piece climax ending; or late, which is just bad period unless the DM contrives to delay the climax point until they arrive.I agree with @Mort. The party with the ranger has more time to deal with the cult, and that is a good thing. The feature is benefiting the party, which is what those features are intended to do.
It's only a problem for the DM who insists that the players need to interrupt the ritual at the last possible second, but also insists on using a clock. In which case the only problem is the incompatibility of those two agendas. It can still be done, but you can't be hamfisted about it. For example, you could have the ritual nearing completion whenever the PCs bust in, but the clock determines some other factors, like how many demons the enemy has been able to summon.