I have low rep on Physics & Woodworking, but not so on Stack Overflow.
I just tried to ask < 40 minute interval on those two and got hit with the once-per-40-minute rule:
I posted once on Woodworking, then ~5 minutes later tried to post on Physics, and was denied because of the 40 min rule. So apparently the system looks cross-network to assess this rule.
It seems the system is looking at my lowest cross-network rep when applying this rule rather than highest rep? What is the point of this very conservative approach? It would seem there is very little chance that a user with high rep on ANY site is likely to spam or abuse the lower-rep sites. And obviously this discourages participation across the network.
Furthermore, an improvement at least would be to warn the user ASAP so they aren't stuck with a nicely worded question in their browser window only which could be forgotten, lost, etc. As it is you only get the warning when you click
[Post Your Question].