I hear what you’re saying about the first item to be practiced ends up getting the most practice time in by the end of the 7 days (if you’re working on 7 scale patterns for example), but therein lies the aspect of continuing for the 21 days. By that time, all the patterns should be comfortable and into our DNA. Because as much as the earlier patterns do get extra practice time in, the extra time (after their initial 18 minutes) is really just for polishing up what had been worked on previously.
I’ve noticed in my use of the process (and noticed in friends’ and students’ use as well) that by the 2nd week, all the patterns are equally comfortable and locked-in.
Likewise, while practicing a new item and previous items, as much as my teacher had mentioned about playing them equally as you build up your patterns, I don’t see any harm in polishing up the newer patterns a few extra times more than the older patterns. i.e. - if you’re on day 5 pattern 5, after your break, you could play pattern 5 for 5 mintues, pattern 4 for 4 minutes, 3 for three, etc. But when ya think about it, it may be overthinking. Any time I went to practice previous patterns after a new pattern, I just made sure all the patterns played and sounded equally great.