That is a lot of bookkeeping and just seems to make martial classes worse. Fighter spends 3sp a day to keep his gear functional and Wizard spends nothing!
I have one GM who gives us a flat fee for maintenance after an adventure based on what we have done. Underwater caves or sewers has a higher cost that a wilderness jaunt. The whole party pay the same.
As for Raw vs Training I would just give out less Gold.
I give my players about one permanent magic item each adventure and a few hundred gold at most (unless they are getting a Dragons horde).
Game economy tends to exist just for the players. Once you have all the plate armour you want there’s not much to spend cash on unless you give them something to spend it on.