Indeed, the wind question is mostly academic as we rarely fly long cross-country tasks in wind speeds that make a big difference. Identifying convergence (and divergence) lines and dealing with long distances between thermals are more useful problems to solve. MacCready theory optimises your speed between thermals but doesn’t tell you what to do when you get low or can't find a thermal (John Cochrane wrote a paper on this too). Perhaps this is something that smarter flight computers could address?

Mike