Your bees certainly appear to be doing well. Maybe you just got lucky for a season.
Last year I used no treatments of any kind, only management technique (slatted racks, Top entrances, plenty of ventilation). I did sugar treatments in Nov (rolls, shakes) and found no mites. Literally none. Total counts of fall in the summer had been minimal.
I have no illusions about the future or the tenacity of this pest and will treat if it ever becomes necessary (maybe api-guard) but for now my only intention is to shift slowly to small cell.
The surrounding operations here are plagued with severe varroa problems. Lots of dead hives this year.