Same here. I’m surprised the Reorder Script has this much bad reputation . I personally think it helps or hinders depending on how you use it, and it doesn’t necessarily make you a WK speedrunner either.
I’ve been using it for a long time to divide what I learn evenly and not spend more than the necessary time on each level (not only to be efficient with my learning, but also because I’m not lifetime). For that, it’s kind of dependant on how many lessons you do per day, though. I also do 20 a day, and I always reach 0 lessons before leveling up, except once, when I had to take one or two more days learning vocab before new kanji.
And even then, if you go by whatever pace, I think the ability to reorder is still very valuable. It means you are not forced to learn so many kanji at once when you level up if you don’t want to. Maybe learning 20 new kanji at once is very overwhelming (I know it is for me), but learning 10 new kanji and 10 vocabulary is very doable. I use the script to take advantage of that and it has worked amazingly.
To answer your question more directly OP, it depends on what pace (lessons per day) you plan on having and how strict you are with not letting yourself advance unless the oldest vocabulary you have pending temporarily is from last level and no more than that.
Details of my process with the script
What I do when I level up, is do the radicals first. Depending on how many they are, I do more or less kanji. For example, if they are only two, I do those two + 8 kanji, and then I do 10 vocabulary; if they are 6, I do 4 kanji, and 10 vocabulary; and so on. The vocabulary I always sort it by level, so it picks items from the last level first if there are any. Next day I do 10 kanji + 10 vocabulary. The next one, 10 kanji +10 vocabulary. 10 was normally the max number of kanji I would do in one day unless I felt I wanted to do a couple more, especially in the last levels I’m currently at.
Once the kanji were all done, the lessons would be 20 vocabulary. And eventually, even if some kanji you did the previous days are entering guru and unlocking new vocabulary, it isn’t enough to pile up, so you eventually hit 0 lessons between level and level. Once levelled up, I repeated the process.