It’s not hogwash, it’s true under the assumption that your burn rate is the same as your new lessons rate. That is to say you make no (or few) mistakes. The more mistakes you make, the more you delay those burn items and hence the bigger your review pile becomes.
You can pretty much forecast this by checking how many burns you have on which day using the wanikani heatmap script [Userscript] Wanikani Heatmap and multiply that by the % you usually get correct and that’s how many lessons you should allow yourself to do (e.g. on one day you have 25 burns coming up, multiply that by 0.8 (assuming you have an average 80% correct rate in reviews), and that means you should do 20 lessons that day. That way your review pile will never grow larger.