score:5
BC Ferries posts a Busy Days Forecast for major routes based on historical data. The information is very limited, though.
For example, for Tsawwassen (mainland) → Swartz Bay (Victoria), expected busy departures over the next two weeks are:
Whether that means you should make a reservation or not depends on your own risk tolerance.
Upvote:4
It depends on how willing you are to wait. Over the weekend, particularly a Friday night outbound and a Sunday return journey you will likely miss a ferry or two. On a long weekend during the summer, you could be waiting a long time.
My two cents worth, 15 bucks is worth the piece of mind.