Huh, I always thought permethrin was just and insecticide. Good to know."somewhat effective"...yes. "better than nothing"...yes.
"...most commonly used..." doesn't mean "most effective". DEET IS the most commonly used insect repellent for EVERYTHING, mainly because that's what most department stores sell as insect repellent.
I worked outside daily in what seemed to be the tick capitol of the world (a Virginia cattle pasture/hayfield) for 5 years, teaching long range shooting. I put down white canvas ground cloths for us to lay shooting mats on, so we could see the ticks coming as they charged us. I have had to remove several ticks a day from my clothing and usually got one embedded about once a week, in spite of using DEET. Rare was the time I wasn't scratching at least one healing tick bite.
Ticks plagued me until I switched to permethrin. Pre-treating my boots and work pants with permethrin, then doing a light refresh each morning made all the difference in the world. I also treated the edges of my ground cloths, which seemed to help deter them.
Very strong concentrations of DEET do work better (as might a very strong concentration of diesel fuel), but also will cause damage to plastics and stock finishes, and are no longer recommended for application to human skin, hence the "10 to 30%" being considered "adequate" (safer and less destructive).