Gmail Notifr allows one to set a larger check interval than 'real-time'. As the author of the app, I set my accounts to check every 120 min (work) and 240 min (personal).
What would be handy in a tool like this is being able to set up what I described above; normally don't ever notify me, but allow me to turn on real-time notifications for particular people on demand, or other rules for knowing when it makes sense to interrupt.