"Playing pedal tones" is not specific enough. What you do with pedal tones makes a big difference in what you get from them. The Claude Gordon exercises (and I suspect others as well) involve playing multi-octave arpeggios beginning and/or ending in the pedal register. This is the best exercise I know of to eliminate the multiple-embouchure problem (shifting embouchures between registers). Correcting this embouchure problem has unquestionably improved my flexibility and endurance, and has probably contributed to my improved range as well.
For those who are familiar with the Arban Characteristic Study #1, that exercise used to be a killer for me. It only spans a couple of octaves (a Bb below the staff to a Bb above the staff, I think). In lots of places it takes you from low c to G above the staff and back down. I had a terrible problem when returning to the lower register--I could not relax my embouchure on the way back down, and I could not get a good fat sound. I was shifting my embouchure on the way up and was having trouble shifting back on the way down. Now I am working on three-and-a-half octave arpeggios from pedal C to G above high C and back down to pedal C, and I am now handling this better than I used to handle the one-and-a-half or two octaves called for in the Arban characteristic study #1. The secret is learning a single embouchure that works throughout the range, beginning with the pedal register.
I've seen several folks post advice to set your embouchure for a G on top of the staff in order to be able to reach up & down to increase the "span" of a single embouchure setting. It seems to me that "setting up" for a G on top of the staff creates too much tension. The approach I've learned is different. My natural lip setting is probably a low C, but in reality my lip, tongue, airstream all adjust for each note.