I wouldn't personally call it hit or miss Bryan although nothing with wind is a guarantee, seabreezes (NW) exhibit fairly predictable pattern once you know what you are looking for.
You are right, if you are not there right before it happens, or soon after it begins, you may as well stay home, unless one hour of riding is worth it to you.

This time of year (past 6 weeks or so) they usually blow for about 3 hours. We are beginning to run out of our seabreeze season (as soon as the dominant high moves east and showers start to happen)