My buddy "Dan" plays a good lead trumpet. I try and feed him as much of the first book as he'll take. He's not only a strong high player but accurate with lots of endurance. To hear Dan's warm up is about enduring fifteen minutes of lip slurs in the middle and upper register. Not the most relaxing of sounds to my ears. Me? I'm the exact opposite. I never play lip slurs or trills in a warm up. Instead I play slow chromatics into the lower register. Then gradually going upwards via scales and arpeggios and scales. I might only go up to a High D or so. Then will let the gig warm me up. Not unless the first chart starts with a ridiculous high note or something. What I figure is that by the time the chart has made me play a few loud High C's and D's? My High G etc. will be ready. And again Dan is exactly the opposite. BUT... But Dan is a forward jaw, dry lip playing screecher. As such he gets a powerful physical advantage. His problem is "getting loose". Or gaining resonance in his chops. Me? I can put out a big tone with good resonance even on cold chops. My goal in the warm up is to lightly encourage my chops. To limber up. Avoidance of excessive tension and a gradual awakening. For me to play a whole ton of lip trills before the first chart would uselessly burn my chops out after the first set of real playing. Not helpful. Conversely if I'm having a slow week with few gigs? Then playing lip slurs and trills is a good replacement for heavy performances. So unless you find a real advantage in warming up with lip slurs like my buddy Dan? Don't do them. I won't even play them a whole day before a major gig. Saving it for when it counts.