so what does everyone do with there empty spools? is it possible to use other filament types on different spools?

ive had my P1S for a week now and loving it! new to 3D printing!! and so im wanting to know other users experience on monthly maintenance (oil and grease etc) and what types should i use? how often should i do it? ive read on Bambu labs support page is monthly - every 3 months but do people actually do it or not? bare in mind im not printing like 10 hours a day maybe 3 hrs a day weekdays and weekends around 8 hrs thank u for any advice given!

im currently looking into buying myself my first 3D printer EVER! what do people suggest?! please bare in mind i have never used a 3D printer before