I sympathize with you, mil. As I wrote about Tactics Trainer in another thread:
It drives me nuts that no partial credit is given for the same number of moves but different move order that is equally valid. Got docked one time for moving the "wrong rook" when either rook would do; I checked it thoroughly afterward to confirm this.
The scoring is unbalanced as well. For example, if you take too much time on a difficult combination you receive a mere +1 for a correct answer, but if you select a less than optimal move anywhere in the variation you might end up -10 or more down. You have to be inordinately quick, even on deeper, more complicated combinations, to get a decent score. Oh, and no sidelines or alternate, instructive variations are given.
I'll stick with combination books and encyclopedias, of which I have a slew.
On that note and to you specifically Mr. Cashen (MickinMD), I highly, highly recommend the book Improve Your Chess Tactics: 700 Practical Lessons & Exercises because it names the common tactics of pins, skewers, forks and double attacks, but explains the concepts behind the tactical motifs of deflection, decoying, eliminating defenders, clearing squares and lines, interference and cutting-off, unpinning and any combination of these. Chess.com's Tactics Trainer does none of that. I say understanding comes before over-the-board practice and is more conducive to rapid improvement, and least it was for me.
I have great ambivalence about Tactics Trainer -- as is clear from the fact that I've spent a total of 21 hours on it in 8 years! I finally got up to 1200 on it recently, and then quit using it for now, because 1200 is such a Triumph! ... and whenever I do go back to it, I know it's going to go down again. (This proves I've got my priorities right - - - right?)