Was I had set trainings for my Ironman training and simply getting on and riding around Zwift world didn't work because I was trying to do something specific.

If I got on and said I want to do a 50k race I think I would enjoy it more.

But my training was usually something like

5 mins warm up
20 mins @ <80 cadence @ >220 watts
60 mins @ 90 cadence
5 mins cool down.

That type of training didn't translate well for Zwift.