Silly question maybe. I logged in a good 400 hours of training last year and this was done 100% outdoors, on hills, trails, etc.
This year I just got into a travel heavy job and I am confined to training on a treadmill at the hotel gym. My question is if the effects on aerobic development are the same or if it really matters if the workout is done on a real trail?
I still have the weekends to do ME outdoors and other long big days in the hills, but during the weekdays it’s quite impossible for me. I have the motivation and willingness to put the hours on the treadmill, even if that means getting up at 5 am.
My goals this year are very low key, I am only planning the Elbrus North Side in august.
We coach many folks who are constrained by time and/or location that are forced to do the bulk of their training on a treadmill. The do well on their goals. I think you should be fine with the mix you are describing.