What is the max time between a metadata request and a submission based on that metadata?

Currently we use some metadata which is valid for the next 4 - 8 GBs of transactions on our network.
If you try to make a transaction based off metadata older than that, the transaction will fail.
I’m trying to work out whether this is going to be an issue for us.

Ah interesting. I’ve never heard of a metadata expiry mechanism based on GBs of transactions produced. Could you elaborate on the mechanism that enforces this?

At Coinbase, our cold storage systems can take up to 24 hrs to sign a constructed transaction (our hot storage systems are much much faster). If there is no way to construct a transaction that is valid for that long, we usually need to invest more engineering resources to work with the asset issuer to find some mechanism that can get us close to that (in the past, we’ve seen asset issuers make protocol level changes to support this).