Tired of junk thermostats. Going with NOS. Do I need to drill a hole in in?

I tested some of the 'Robert Shaw' stats a few years back. The Chinese versions that have the s/steel bridge. I found they opened at the rated temp & did go the fully open position. All good. If the engine cooled down, they did not fully close at the rated temp, stayed open slightly. Temp had to drop further until it fully closed. I switched to the Stant Super Stat & opens/closes bang on the rating.