I think you need to define what you want to do, what that is "worth" and then make a decision. There is no substitute for practice time, but 90 minutes well spent can give you enough time to make most listeners happy most of the time. Divide that 90 minutes up into 30 basics, 30 tunes and 30 technical - in that order. The basics are breathing, long tones, lip slurs, scales, easy articulation. Tunes are self explanatory. Technical is Arban, Clarke, Schlossberg, St. Jacome, Hering...................... Play tunes in the middle! Always try to put them during a time where your chops and mind are fresh. Any time you get an opportunity for duets, go for it. Nothing will improve your playing more and faster than intensive ensemble work. You like jazz, find a bass player to jam with.