I also spray my hiking/yardwork pants and boots with permethrin. DEET is pretty useless, I’ve seen them walk right over DEET sprayed boots onto my pants. They make it about 5 steps through permethrin. I’m surprised advise from Harvard is getting this wrong.
If you want even more protection, you can buy stocking like slacks and a shirt specifically made for this purpose on Amazon. I wear these when I’m weeding or clearing brush.
All the above methods haven’t failed me in 5 years.