I have washed every year since the first year I did it. I never did back in the day, as I didn't know it was a thing. There would be years where I could barely smoke my own bud because it caused me to have such an allergy attack, I have pretty rough seasonal allergies, the main ones being pollen, dust an mold... as you can imagine, pollen, dust and mold spores stick beautifully to sticky buds. Not to mention the various critters and critter poo, because I also grow organically, I preventative spray, but there are always gonna be some bugs unless you saturate daily, plus you get the unfortunate flying passersby that lands and gets stuck... I leave the spiders and ladybugs alone to do my bug killing dirty work.
I do the 3 bucket method, well 3 tote method cause I do it by the arm when possible. I wet trim first, tap off clippings by smacking the stalk or the buckets get gross with tons of trimmings. Bucket one, baking soda and lemon juice in lukewarm water, bucket 2, very light peroxide wash since I almost always battle mold of some kind at some point. I always amputate or chop when I get botrytis, but I'm paranoid. Bucket 3, plain cool water. Dip and gently swish for about 30 seconds each, drip in between, change water when it gets gross. I twist the water out gently, like you do with an umbrella, hang them on upside down tomato cages and hit them with fans, they get moved to the drying area when they stop dripping. It adds a lot of work to the harvesting process, but I'd rather do it and be able to enjoy my smoke without allergy attacks. I have a dehumidifier in my dry area to make up for the extra moisture, but you need good air circulation at the bare minimum, because they can mold in those first few days, but that's any time you're drying really. It does knock off a few trichomes, but I think it's negligible overall, and it's a trade off I have to make or I risk a year of weed that makes me get watering eyes and sneeze attacks... which I'm not down with.