Quality of Off/Def weapons maint and supplies

Hello

i have 2 questions

1. lets say i have a unit of 300 quality planes and they sit doing nothing

but the off/def weapons maintenace that the country buys is 120. do plane quality go lower in time ?

2. same question about trucks , supplies, aircraft fuel in units.

what about the monthly military supplies that country uses ? if they are quality 120 do they harm weapons quality ?

thanks