Scar's trim chart is written by pattern flyers for pattern models.

The procedure I use for sport or scale models is to trim out the model at half throttle in straight and level cruise. Then bring it in on a nice steady straight approach and at 10 to 20 feet go to full power for a go-around.

If it climbs out and turns left it needs right thrust (assuming conventional layout).

If it turns right it needs less right thrust.

If it doesn't climb out (dives for the runway) it needs less downthrust, or maybe a further forward CG (or both).

If it climbs TOO steeply then it needs more downthrust.

What we want is a smooth transition into a straight climbout at a slightly higher airspeed than the approach. It may initially need a nudge of up elevator to a nose up attitude but should not need much trim change.