...you will slowly learn the notes and some rhythms. You can develop a fairly nice midrange sound if you simulate a good example, like a teacher. You can have fun. Many beginners, junior high trombonists, and some high school players practice this way.
On the results of practicing 10 hours per week for several months:
...you will notice some important and valuable developments in your playing. You will become more "fit." You will handle 5 or 6 books at a time, or more...Your reading will really improve! You won't be sore the day after a big blow. You will use the metronome, mirror and tuner properly and do dozens of flexibility routines, scales and arpreggios. If you find something really hard, you will have time to work it out, and work it up. There will be time to solve bad playing habits.As well as the pride of learning an instrument well and the satisfaction of playing great music at a high level.