Our company flies the B-737-400,500 &700. I have not heard of the 50' correction but I can see it makes sense. But we do correct for temperature and wind to all minimas (In our environment that can be a lot). On our non-precision approach charts we have a table which gives us a stable descent, which gives us a 3 degree profile from MIN to touchdown zone. And flying EFIS we always put our minima at the closest 100 feet above the minima.
And to respond to "wondering"; on the 400 & 500 it is wise to use HDG select on the final intercept due to the lack of IRS ground stations update which we experience frequently at lower altitude. Which again causes frequent map shifts. Of course the non-flying pilot is checking by raw data.
However on the NG -700 map shift seems to be history so flying L-NAV Seems to work fine.