In terms of repetitiveness, really the SRS system kinda handles that automatically. Admittedly, it doesn’t reduce repetitiveness to zero! But my point is simply that if something is easy, then you can answer it quickly and move on quickly, and the interval between gets roughly doubled. Only takes a few repetitions before you get to intervals of a week, two weeks, a month, whatever.
For someone who already knew all the kanji and could answer them all without any mental effort, then they could complete all 60 levels without any mental effort, and it would all be ‘repetition’. That’s the worst case scenario.
But for someone who is ‘illiterate’, surely (by definition) there will be kanji they don’t know, and after they get through the first few (or maybe several) levels, they will surely begin to run into kanji they don’t know at all, and having a systematic, organized tool/site to keep track of their progress, help guide them through a ‘plan’ (order of which kanji to learn first, second, etc.) that is geared towards adults (young and old) rather than young children might be useful just to keep them motivated and on track. They will quickly ‘find their level’, and from there they can proceed at their own pace, whether that be banging on through to level 60 at top speed, or maybe taking a more relaxed pace Durtling the Scenic Route 
.
I’ll give an example: I’ve recently taken to revisiting old friends on my scenic journey learning Japanese. Essentially that means resurrecting previously ‘burned’ items from earlier levels that I don’t mind ‘repeating’, 1) because they are pretty common words, yet I still couldn’t recall even after ‘burning’, 2) because I sometimes want to fill in ‘gaps’ or ‘holes’ in my Review Forecast, but I don’t want to ‘rush’ the current level by filling it with new lessons. In other words, sometimes even ‘repetitiveness’ can be a soothing/comforting thing rather than always being an annoying/frustrating thing. It all really depends on one’s perspective, goals, and desires.
If this is someone who is currently getting along mostly-just-fine with being verbally fluent in daily life, but wants to learn Kanji as a personal goal (rather than, say, in a hurry to learn it for school or work purposes), then maybe they would actually appreciate a ‘gentle’ slope to the ‘learning curve’, and maybe ‘repetitiveness’ is actually something they might even enjoy, in the same way that many hobbies can have repetitive elements to them (practicing a sport, knitting, sewing, crafts, woodworking, even many arts, even something like reading can have repetitive aspects to it!).
I’m not saying that repetition is always ‘good’ (not at all!). Just saying that it’s not always ‘bad’. It really depends on the person and their personal goals, IMHO.