Yes, you can change IDEBuildOperationMaxNumberOfConcurrentCompileTasks by setting defaults write com.apple.dt.Xcode IDEBuildOperationMaxNumberOfConcurrentCompileTasks 14 or whatever, and this will effect all Xcode builds that start after that. Also, this will effect the command-line xcodebuild (but there, you can control it for each build with -jobs argument).

Did you specify inputPaths and outputPaths for your scripts?

I am not sure I understand your use case, but for me, I simply need a way to inject a custom header into requests that are handled by a WKWebView. With NSSelectorFromString(@"registerSchemeForCustomProtocol:"), I can do that for all WebViews in my app, but it would be OK to have to set this interceptor for https scheme for each WebView separately. I really hate the idea of having to modify the HTML content of each WebView with some javascript only to replace the https scheme with some custom scheme (then, I can use the documented setURLSchemeHandler as @eskimo demonstrates in another thread). Any hints?

What we ended up with, run a small custom script - https://gist.github.com/alexcohn/53fb9e93699080f158b5721888edd578 as a pre-compile build step for each target that depends on the xcframework. The naïve approach is to check that the directory exists. It could be improved by triggering a build of the default target of the project that produces the xcframework, and proceeding to the script if that build is not nop.