I left it all in first couple of batches but have been straining ever since. I actually like my batches of strained wort better but the better quality is likely just due to the improvement in my brewing skills. I have only brewed 6 batches in total.
I think you can go either way with it, your preference, but certainly no harm in leaving it in. One thing to remember, if you boil less than 5 gallons and have to top off your wort with water, you need to bring the frementer volume up to around 5 1/2 gallons or so to make up for all the volume taken up by the hops and stuff.
Let me eat when I'm hungry, let me drink when I'm dry
Two dollars when I'm hard up, religion when I die
The whole world is a bottle, and life is but a dram
When the bottle gets empty, Lord, it sure ain't worth a damn