I also have a 3AJ that holds 2.8 - 2.9 litres of oil, and I also never touch the bleed screw.
I have wondered whether I was doing the right thing, but on the one occasion that I bled the oil filter cavity as per the Clymer manual I was worried about over-tightening it and stripping the thread or under-tightening it , the screw coming out and loosing the oil supply to the top of the engine.
So I removed all traces of oil from the screw & thread and stuck it in using medium strength thread locking compound.
There is a gauze oil strainer in the oil tank, it can be seen inside the tank once it's drained. This can be removed and cleaned by removing the appropriate oil-line once the tank mounting bolts have been removed to give some slack. Don't lose the o rings between oil line and tank and make sure that they are seated correctly when you re-assemble. I don't do this every oil change, too fiddly.
I fill my oil tank, start the engine with the cap off and add the remainder as the level drops. I change the oil often and the filter every second time. I drain the filter housing by removing the covers bottom bolt, don't touch the other 2, you see an extra drop of oil trickle from the drain plug a few seconds after removing the screw.
I have not been able to find a gauze filter on the XT600E.
You can buy a hellicoil ket and repair the thread yourself, its not difficult but if you only have one thread of that size to repair it may be cheaper to pay someone who already has the tool to do it.