I hate to be that guy, but if you're looking for a simple way to defend yourself from too many meetings and/or conflicts, my startup might be interesting to you.

Our first product, https://lifeworkcalendar.com, blocks out your work calendar when you have personal events. And our next product (coming soon), https://reclaimai.com, does a whole bunch more to align your calendar to your priorities.

Email us if you're interested in a demo -- I love the Hacker News crowd and our target audience is busy managers/directors/VPs in product orgs :)