There should be a progressive increase in timing with revs to allow for the extra time needed for the flame front to travel and burn the mixture. Therefore each increase in rpm should have an increase in timing. The point at 4400 on your maps actually goes down. Maybe that was to fix a det issue but the correct way to do it would to be smooth the surrounding cells to still allow this logical increase.
The timing should also logically decrease with increased load.
This is a screen dump of my base timing map:

You will see a natural and smooth trend in all directions.
This map isnt finished but you can see a difference between that and yours shown below:
