No. Look up Arenas. In general group allocations to avoid making a mess.

If you send a task off to a work queue in another thread, and then do some local processing on it, you can't usually use a single Arena, unless the work queue itself is short lived.

I don't see how arenas solve the problems.

You group things from the same context together, so you can free everything in a single call.

No. Arenas are not a general case solution. Look it up