> I think a better idea would be to steal from DNS and use TTL and serial numbers (maybe just standard http last-modified is enough?)
HTTP already has an Expires header: https://tools.ietf.org/html/rfc7234#section-5.3
Seems like a better solution that would accomplish the actual goal would be "refresh-after" where you could specify how many days a client should wait until asking again.
Zero maintenance required but still gives a rate-limiting and time window function.
The last thing I need is one more thing to have to remember and update.
By the looks of it, a few others feel it is non-critical and have just skipped it too.