Foam boards are highly effective for insulating exterior walls, basement walls, attic hatches, and other parts of your home.
Drying time for wet insulation depends on type, ventilation, temperature, and humidity. If it doesn't dry within 2-3 days, it should be removed to prevent mold and wood decay.
Use R-13 or R-15 kraft-faced fiberglass or mineral wool insulation for 2x4 walls to ensure proper insulation.