Can Webhooks be updated (if they have not already) to work at site collection level?
We have a solution that tracks lists across multiple subsites within site collections. With Remote Event Receivers we have been able to monitor this with a handful of registrations (I believe 5 currently per site collection). An example of one client where we see this being a problem is, they currently have around 1,700 subsites in their site collection, approx 25 lists in each site. My understanding is that we would have to register a webhook against each list (42,500 in this case), which we suspect will result in a lot of throttling during the process.. It is possible for additional subsites to be created, or for lists within those existing sites to be removed and recreated or additional lists added - As a result, regular checks would be required to make sure all lists in all subsites have webhooks registered against them - a lot of calls, and a lot of throttling.
It may be there is a better approach to this using webhooks that we are unaware of, we would be happy to look approaches if anyone would be kind enough to point us in the right direction. Any guidance would be must appreciated.