Ironhorse, what do you suggest you should practice in those 15 minutes? Not being sarcastic, really want to know. I agree with everyone on this thread, though I have been riding most of my adult life, I have picked up some great things just on this thread. You can always get better and on a motorcycle and just 1 slight mind screw up can be catastrophic..
That's a good question, not a sarcastic one.
Like all things, work on the basics like head turns and eye placement. Remember hands and feet operate the controls, head and eyes command where the bike goes. Get used to snapping your head around and looking where you want to go. This can be done with simple u-turns, circles, or figure 8s. This translates to corners and curves as you must turn your head and look through the turn for the exit. Work on good threshold combination braking complete with follow through. Braking practice can be done at 15 - 20 mph. Work in getting a feel for the bike when it's leaned over and moving under you. Work on riding in the friction zone and slow speed maneuvers as these improve balance and coordination.
Practice is taking the skills you have and the lessons learned, and working on them to maintain proficiency. Think of it like this. If you do not practice tennis or golf regularly, do not expect to hit the greens or court and play as well as you did when you finished up your lessons a year or two ago. It's just not going to happen, especially at our age. Now if you screw up on the greens or the court, the worst that can happen is that you loose the game and strain some muscles. If you screw up on the street on a motorcycle, the losses will be significantly greater. The only difference between an average rider and an above average rider is practice.
Practice will lower the odds of that 1 mind screw up you referred to.