Thanks for the quick response. Yes, I am using mirror mode. Yes, I am using 50 ms. It's fine if you can't make it any faster...but it is only a problem/concern when you are clicking on a mahogany plank that was just created and not the log behind it. An easy fix would be to start from the bottom and work your way up instead of trying to work from the top.
Edit: even though mirror mode is slower..... manual plank make is theoretically clocked at 1.8 seconds compared to a 3 second automatic plank make timer. If manual plank make is not generating 140k xp per hour, it doesn't make sense to use it. The risk vs. reward of 90k xp/hr(current automatic plank make average) and 105k xp/hr(current manual plank make average) is too high.