I can attest to this.
My son completed the 4th and 5th grade courses. They took about a year in total (5 months plus 7 months IIRC). During that time, I spent maybe 30 mins per week giving him some additional explanation. (At school he was studying Singapore Math 3A and 3B, which don't overlap much with these courses.)
If MA didn't exist, I would instead have my son speed run Beast Academy 4 and 5, to make sure he has no gaps, and then I would then need to tutor him 1:1 using the AoPS Prealgebra book, which is good, but a bit thick and intimidating for a child to self-study.