It very, very much is. I’m technically in the “fast” levels right now, but I’ve done every single one of them at my usual two-week pace, and I think that’s a very good idea.
Not only are the items up here generally less common/“useful”, but they also tend to be harder to memorize, too. Lots of more abstract kanji meanings and vocabulary that’s harder to remember, coupled with it also being less common and therefore less likely to show up in your immersion.
My accuracy on the higher level items is a lot lower, so despite taking the levels at a pretty slow pace, I’ve still seen my daily review workload increase a little over the past month or so. I can’t imagine trying to get through these levels at maximum pace without succumbing to the temptation of cheating your way through with the double-check script. I think speeding through the last set of levels is a great way to set yourself up to burn out on SRS, honestly. Obviously that won’t happen to everyone who tries it, but I can’t imagine it not being a miserable experience, and you don’t want to get to a point where you’re dreading even opening up your study tools.
Yes the load drops really fast after that. The review count for the coming days is ranging from 60 to 186 per day. During the fast levels I had an average of 400-500 reviews per day and on top of that had to learn all the Kanji and vocab within 3 days.