I usually get a fish on every drift because I am a very experienced angler. I am very experienced because I am fortunate to spend a lot of time fishing. Some months, that's several hours daily.
On average, even the strongest Chinooks take me less than 10 minutes on 6lb line. My guiding service, on average, will be around 2 to 3 hours. This is because myself and my clients will be driving a fair distance to the locations. In order to make the most of the time with me, I recommend they set aside a couple of hours. It may take a novice angler some time to land a salmon.
If I accidentally snag a salmon (or steelhead or any other fish), I usually break it off immediately.