Personally, I find myself having to think about some items for up to 5 min. Now, while 5 min is a rarity, it’s not uncommon for me to need 30-90 sec to think of the meaning/writing of a kanji/vocab/radical. I’d say every 20-50 or so I get one where I have to sit and think about it. So 100 reviews take me about 30-45 min. I get gassed out after about 90 min of reviewing.
I do it because I usually manage to remember it without any clues and AFAIK that’s the best way to tell my brain it needs to remember this vital information or else I won’t survive
Just to clarify, some of them, as soon as I see them, I just know I don’t remember it and I don’t sit there trying to remember something I simply don’t know. It’s that tip-of-your-tongue feeling …
I typically do about 8 to 10 reviews per minute. I’ve done 300+ reviews in one sitting, although I tend to really struggle to get through those last 100. I believe 200 is the max amount of reviews I can “comfortably” (more or less) get through. After that, I’m usually spent.
I never do all the lessons. Just do 5-10 from the lesson when I feel like it so my reviews never get crazy high especially if I am doing them daily my review numbers are pretty slow. From the burned items I have 100s of burned items and one time I did around 600 in one sitting and felt my brain fry, so I always just review 50 from the burned items per day and seem to handle that just fine.