I found one photo I took showing my 3mm wood cut tests. For these test cuts I manually wrote the gcode and did make the speed adjustments necessary to make the cuts come out even. This means the two cut lines running along the grain cut 100% through the 3mm wood AND the cuts against the grain also cut 100% through the wood...but I had to varying the Feed Rate in order to accomplish this.
I'm also attaching the same photo but with added notes showing what happens to a cut square if you use the same feed rate for all line cuts.
For clarity, those squares that did not cut 100% through the wood, this photo is showing the under side of those cut attempts. You can see two lines cut through and two lines did not.