I realize that there are some teachers and books that advocate the use of pedal tones to help extend your range.
I am not one of them for several reasons.
1. 90% of the people who play pedal tones allow their lips to roll out or protrude into the cup of the mouthpiece. Both of these are contrary to the action needed to play high. Pedals are fine if you maintain a correct embouchure however someone needs to watch you play or you must use a mirror to advoid embouchure shifts.
2. Pedals will not build muscle needed to play high. Even when played properly pedals are played with much less tension than high notes. Only playing high will build the muscles needed to play high.
3. How many pieces of music require the use of pedal tones? If you never need to play them then why the extra practice?
4. The amount of air pressure and air speed used to play pedals is different than that used to play high.
5. If you play until you are tired you should rest. However many people will play pedals are then continue to work their chops. Some of them have injured themselves by doing this. The lips are still fatiqued and weakened however by playing pedals you have increased the bloodflow to the lips and removed some of the lactic acid. Lactic acid is produced by all muscles when worked and the build up signals your brain that the muscle is tired by making it sore. When you speed up the blood flow and remove the lactic acid then you fool your brain. You no longer feel all of the muscle damage until the next day. Most trumpet players have experienced this. To do this on purpose is inviting disaster. Yes there are some range books that advise this, but I can show you how to improve safely.