I grew up with cassettes and d90 mixtapes. 45 minutes a side (47 if you were lucky) to capture a theme and hold attention. Then cds brought 70 minutes and then 80. All my mixes are limited to less than 80 minutes to reflect my preference for in car stereo listening (no Bluetooth or ipod docks for me). I hope if you happen across my mixes that you like my hobbyist attempts...