I started 5 years ago and still very much consider myself a novice. At our local association beginner's course it was drummed into us " if you want to keep your bees alive you must treat for varroa ". I find myself constantly apologizing to my bees for my clumsiness, but I am getting there. Never lost any yet apart from a late nuc and my first hive was lost to vandals. I lose the odd swarm, but always get a reasonable amount of honey ( although this year it could be thin on the ground) and I firmly believe that is because I treat for varroa twice a year, which is strengthened reading comments on this forum. Our local commercial guy George Hood (deceased) said he never saw any mites but he always treated for them.