I agree it's definitely possible for some students. There are students who finish standard 4-year CS degrees ahead of schedule by taking overloads every semeste

I agree it's definitely possible for some students. There are students who finish standard 4-year CS degrees ahead of schedule by taking overloads every semester (which sounds like your case), even at programs considered rigorous. But designing a normal/median path is different thing than saying a handful of top students can breeze through this faster than normal. If you just took the current UT-Austin CS curriculum but made 21-credit-hour semesters standard so you could advertise it as a 3-year time-to-completion, I'm pretty sure it'd be a mess, with some students finishing faster, but also a big spike in dropout/failure rates.