I advise most shooters to either lift the thumbs off the weapon or allow them to drop naturally forward. Lifting the thumbs is preferable because it removes a point of leverage for over-gripping which always results in a inward and downward torquing motion. It’s harder to over-grip without the thumbs. Not impossible just harder. What lifting the thumbs additionally corrects is trigger-push. Shooters who shoot 1″-2″ to the weak side of the bulls-eye will get an instant correction by lifting the thumbs. Some shooters may simply allow the thumbs to drop forward and minimize over-grip. However, the overwhelming majority of shooters ought to lift their thumbs. Many shooters lift the thumbs or allow them to drop forward and receive no benefit from those actions. The reason being those shooters strain the thumbs rather than allowing them to simply hang. The principle is to minimize muscular influence on the handgun and straining is muscular action.
Once again, a vampire has risen from the dead in shooting instruction. Every now and then, some poor soul (who should not be instructing) turns marksmanship orthodoxy upside down by reinventing some old shooting error as a new “practical method.” The current foolishness is crossing the thumbs. There is no good reason to cross your thumbs when shooting either a revolver or pistol. In addition to having a rebounding hammer or rearward traveling slide tear your flesh, crossing the thumbs breaks the weld of the hands. You can test this by joining your hands together as if holding a handgun and then crossing your thumbs. You will see an open space appear between the bottoms of your palms. The hands need to come together, crossing thumbs separates them.
Friends, old boring stuff about shooting is often based on generations of successful shooters. We still have improvements ahead of us but they won’t conflict with proven fundamentals. Test everything. Marksmanship is based on logic and reason not old wives’ tales and intuitive art forms. Let’s be critical consumers of shooting information.