In pieces that present difficulties with endurance, it is very important to actively seek out and find "chill out" times where you relax the dynamic and pressure of the mouthpiece on your face. I can remember having a lesson with Nitzan Haroz where we were working on the Martin Ballade. After I missed the high D at the bottom of the first page, he said, "I could tell by the way you played what came before the D that you weren't going to make it." The reason is because I had played the preceding music too heavily. Even the strongest players, like Nitzan, consider finding ways to allow their chops to "take a break" in the middle of these difficult works. Try to get out of the Superman mentality. It generally doesn't work, and if it does, it won't for long!
When playing chop busting pieces like the Martin, Creston, Tomasi, etc., be constantly aware of the toll you are putting on your chops. Make sure to take full advantage of softer sections as an opportunity to stop the heavy lifting, get the circulation going again and cycle lactic acid out of the musculature. A healthy vibrato in places that are musically sensible can also be helpful. Last but not least, nobody wants to hear these pieces played heavy and pressed from start to finish anyway. The variety makes everyone happier!