depends on the relay. damus relay will rate limit if there are bursts of posts all at once, but otherwise there are no daily caps or anything.

You can connect to any relay that implements a rate limit policy that suits your needs. nostr gives you the freedom to choose, there is no centralized decision making here. nostr:note1jrsjwcldc47qqdxpequpjns7qj98g5he7rzuqa6vdte4fvvrmgfshj290f