Back when I was trying to calibrate my 65VT50, I found that using a 5% size window with an 18%-23% surround, would move the gamma curve so that by using a gamma setting in the VT50 of 2.4 would be very close to 2.2 in the calibration software without much adjustment.
When I used a 5% windows pattern(without the APL surround),I'd have to make some pretty large adjustments to achieve a 2.2 gamm. I think what was happening was that the extra energy that would have gone into the surround wound up brightening up the windows pattern, thus making the adjustments more severe to push it down. Those calibration I thought looked dark even in a fairly dim room. Additionally, if you're making severe 10 pt white balance adjustment, run a 20 pt white balance and see what your inbetween points are doing. There was an article back during the time that the VT30 was the current set that recommended only doing a 2 pt as attempting to do a 10 pt could possibly hurt as these values shift around as the overall brightness of the scene changes.
In case you don't know, this whole which type of pattern has been argued to death here on AVS. I figured that even if I wasn't doing it the most correct way, I like the picture better anyway and I don't find myself thinking that the picture is too dark.
Best of luck figuring this out.
Samsung 64F8500, Panasonic 65VT50, Oppo 95, Tivo Roamio for OTA, Dish VIP722, Marantz AV8801 preamp, Rotel Amps, Atlantic Tech 8200 speakers, Seaton Submersive HP, Calman 5, Chromapure, VideoForge HDMI II, i1Display3pro, i1pro2, eecolor colorbox.