It's difficult to advise without knowng more. How much riding have you done? Hours in the bike in a typical week? Do you have a heart rate or power meter?

Junk miles is the term usually used to decry long, lowish-intensity rides that don't accomplish much. Actually it is often a misnomer, because if you have the time, training for long hours at low intensities is an excellent idea. But keeping the "junk miles" concept in mind does at least remind you to train with a purpose, and make sure that the easy rides are easy and the hard rides hard. Constantly going medium hard, which many people do, is a poor training strategy.

Z1 is usually described as recovery ride pace.