One guys horrible is the next guys okay.
I think ATP has figured out how to min standard all the ratings and set up an in house CFI program to keep it all rolling along.
I don't think 90 days from PPL to CFIMEI, and going right into instructing, is very good system for producing excellent aviators. But you get your ratings and build your time.
As always, no matter what school you go to, the biggest factor is what YOU put into it and the second is how good your CFI is.