A few random appends to consider- working for the utility we deal with these things all day most days and a daughter (despite being more of an indoor kid) with Lyme brought me into this mess deeper.
Spraying varies with application. Aerosol gets better coverage, but a small pump sprayer or a dip saturates. This has a lot to do with longevity, as does moisture exposure after Permethrin is dry.
Getting the inside of your pant leg bottoms, belt loop/waist and boots helps.
Using both an insecticide and a repellent helps a bunch.
Mosquitoes aren't as creepy as ticks but are nasty sluts of disease as well.
There are lot of tick diseases and the symptoms vary. One person may be mildly effected, the next chair bound.
I have sound the Permethrin liquid applied with a small pump sprayer and then Off or Picaridin to do well.