Im strill working this out too…
using 3w emblaser1
I manily use 3mm ply and I find sometimes 13 passes @ 7mm/sec cuts through enough for it to work.
However sometimes I take the ply out and there a patches where the laser has not penetrated due to the wood itself (knots/ glue/ resin etc)
If i go at 4mm/sec I can usually cut right through in 5-6 passes if its a simple shape. but again more complex shapes tend to need more.
From 4mm/sec and less there is noticably thicker charred lines which air current can help reduce.
From 5mm/sec and above the lines are generally quite clear and clean.
My final conclusion for my diode and machine is to really spend lots of time focusing that laser in - use magnets to hold the ply flat - and i go at 100%power 4.5mm/sec with 8 passes. generally this works pretty well for me.
A lot can depend on wood though - i have some 1.5mm ply and its harder to cut because of the glue etc…
Hope this rambling helped !