On my last solo back-pack (for me, major), I used sandals on mountain trails, before switching to mountaineering boots for alpine off-trail travel that included small glaciers and generally fairly horrific terrain.

I feared that the heavy boots would create blisters if worn for full trip, given my relative lack of conditioning.

Total milage was about 25. Trail travel was maybe 12. I ended trip tired, but with happy feet.

I've since ditched leather mountain boots for synthetics with Superfeet insoles. Would still avoid these for extensive trail travel, but they are 100% improvement.