I'm fairly new to salmon and steelhead fishing (but 20 years of trout fishing) - so take this with a grain of salt...
Just to clarify your question - I think you are asking in the context of fighting a fish - not in the context of doing the actual fishing - right?
When fighting any fish, my rod tip is up most of the time. Only when I need to steer around an obstical or when the fish takes off on a run would I drop my tip at all.
I tend to fish light line, so I rely on a good rod to handle to load of a large and/or aggressive fish. Especially when fly fishing and using a light tippet. That's why most meat fisherman who don't have a net drag the fish onto the rocks a ways (with a bent rod) before wacking it. If they tried to grab the line by hand, the fish could easily snap it - a bent rod will buffer sudden lunges and runs. (I guess a good drag can do this, but I think you need to rely on both the rod and the reel to fight the fish)
Some people like to lay the rod sideways at times (still bent at the same angle) for a few reasons. One is when a fish is jumping, they want to try to keep it in the water (since head shaking mid-air is a likely time for the hook to pop out). Personally - I say let them jump! That's half the fun of fishing is to watch the acrobatics. I'm planning on letting it go anyway... (usually)
The other time some (me included) will lay the bent rod sideways is to put pressure on the fish from different angles to cofuse, frustrate, tire, and ultimately to give up in a timely manner. Noodle rodders really need to apply some kind of a strategy like this, since they can't just horse it in like those with stiff rods and 20lb line.
Well, that's my .0002 cents...
In the end, do what feels right for you and have some fun!
-Chad