In the painful levels the number of new radicals goes down, so more kanji will re-use parts and the kanji will start to resemble each other confusingly. If you tried to just vaguely remember the shape the moment of truth will come that doing that is not enough to distinguish stuff like 輪輸 or 微徴. Learning kanji is basically about finding tricks and shortcuts to remember them, and to focus on the important parts (an eye for details maybe) instead of just going with brute force.
Concerning the number of new lessons, I would advice to really focus on the kanji readings and meanings, most of the time you can directly map them to the vocabulary, and learning new words turns into “戦争? War+conflict=war, makes sense … reading as expected …” and the pile of new lessons will start to look less scary.
Other than that, same advice for everyone, get my similar kanji script [here] and phonetic hints [here]!