Lessons learned building a sweeping system
It's an expensive computation that's already solved by your indexer. Don't have an indexer?
You probably should if you're building on-chain, at the very least for internal reporting, BI, and tax purposes.
Then, let the indexer handle indexing events properly, and let your sweeping system focus on watching state.
Nonce management vs batch transactions.
Don't rebuild nonce management.
Key rotation.