My 8th-grade science project was doing a "statistical" analysis of X/Y/Zmodem transfers (and Kermit, I think?). It did well enough to get me to the county science fair here in Dallas, at least.

And yeah, Zmodem was mind-blowing for us.

Ymodem-g (I think I remember that correctly) was faster than Zmodem - but if the CRC failed it aborted the whole send. Often I was willing to take the risk. (at 300 baud that adds up)