Learning how to figure out sharp $\mathcal L^p$-estimates of nonlinear differential expressions, to prove and use them, is a fundamental part of the development of PDEs and Geometric Function Theory (GFT). Our survey presents, among what is known to date, some notable recent efforts and novelties made in this direction. We focus attention here on the historic Morrey's Conjecture and Burkholder martingale inequalities for stochastic integrals. Some of these topics have already been discussed by the present authors  and by Rodrigo Bañuelos . Nevertheless, there is always something new to add.