I'm a Linux kernel maintainer. Conflicts happen, but git makes the resolution straightforward, and can even try different merge strategies (git merge -X "ours"/"octopus"/etc). I wouldn't ever describe it as having been "merge hell". Maybe if it were a different SCM.

Linux has the "linux-next" tree, which merges feature branches together every night; Stephen Rothwell fixes up context conflicts in that tree which saves a lot of time, and the e-mails he generates also function as a notification that the code you're working with has conficts.

Having a nightly merge of all feature branches seems like the right kind of granularity of notification to me.