What is your accuracy? I don’t know what the sweet spot is, but I find if I am too ambitious, and do too many lessons my accuracy drops off. Partly this might be because my brain can only cope with so much info, but is also partly because I only have limited windows of time to give, so if I have too many reviews they end up being rushed, or pushed to the end of the day.
My thinking is that if your accuracy drops “too low” the ratio of time-spent-on-reviews to kanji-learned becomes less favourable. You are better off, especially if you aren’t desperate to speed run through, trying to do few enough lessons that your review count is manageable and your accuracy rate is “better” (I suspect the number here is a matter of personal preference, I wouldn’t want to say you have to be getting x% right or you are going so fast, especially given how early I am in my own journey!).
I know I couldn’t do 200 reviews a day, my accuracy would fall, I’d have no opportunity for other learning, it would stop being fun and become a grind for me etc etc. For me my sweet spot is maybe around 75, that means keeping my apprentice hovering around thirty, which in turn means doing a batch of five lessons a day on weekdays. I do more at weekends and let my apprentice count go up depending on what else I’ve got going on. I am on a super slow track and that probably isn’t right for everyone, but I know it is right for me right now, and I think it is sustainable in the long term.