Email Meter is great for understanding your mail flow patterns, allowing you to decide where you can optimize your time.
I'd like to highlight some metrics which I think you could find particularly useful:
A heatmap showing your busiest hours throughout the day over your report period. This can help you identify at what times you are receiving the most emails, as well as what time you are at your most productive.
Messages by Day
A breakdown of your message volume, showing both sent and received over each day of the report period. This allows you to see which days you were the busiest over the month.
By using these two metrics you can identify when your busiest hours tend to be, and what part of the month can be particularly busy, helping you to plan accordingly.
In terms of reducing wasted productivity of the always-on ad-hoc approach, I've written a blog post about Inbox Zero which I think you could find useful.
You can read all about our metrics in our Monthly Report article, or all about every one of our features in our Help Centre!
Please let me know if you have any questions and I'll be happy to help.