Longtoss during offseason

Should I be playing longtoss as much as possible during the offseason?

Can you come up with any reasons why not???

ive heard that your arm needs an offseason

This is correct.
You need to take at least a month. Many recommend as much as three.
Depending on how old you are ,3 may not be practical…but in off-season, long toss is great. So you can have both…long toss and “active rest” (The term used by UNF…they expect you to “do” and be active just not throw).
You said as much as possible. When resting…rest. Do something else, swim, ski…be active. Off-season in little league is the time from the end of All-Stars until fall ball…depending on the area you live that could be from July til Oct. which leaves time for both…as you get older…my son used to shut down in Nov and pick it back up going into UNF’s Christmas camp, because hs summer ball and travel…He long tossed in and out of season.