So I am up to a total of 8336 tactical problems completed in my quest on CT-ART 3.0. i've just finished my 7 concentric mazes with the level 80 problems with the following results.
I am finding with the last couple of levels, I tend to do the 6th and 7th iteration back to back and that seems to give me favorable results. For instance, the 6th time around on level's 60-80 took me about 2 hours while the seventh only took an hour ( or less). Grant it, these levels had less than 100 problems and level 80 was no doubt the shortest with only 44. I suspect hitting a 91 percentile on the seventh round shows I was able to retain more in my small short term memory.... oh well. I am heading to the 90's. I just may very well have the circles done by May!