Just a lot of variety, goals and thought process. If it´s fun you´ll do more. Also add in rounds suited to competition if you compete, like 5 x 3 with 1 min breaks. And random drills which you can google. Like 1 10 minute round. Or 1 maximum tempo 1 min rest for 5 cycles. Or things like flow work, technical, power, pacing ect. And praciticng techniques you need specifically. Like a round in fight simulaiton based, or switch stance round, or a round with a lot of jabs. Or even like serious of 10-20 repeating a strike trying to focus on clean technique. It´s always uefull to work on the bad, not much you should do wrong there, granted you got some technical instructions.
How much depends on how much you got time, motivation and can recover from. More is better unless you underrest or exhaust yourself in a unhealthy way.
It can be simple, Thais just punch and kick stuff, be it bags pads the air or each other for like 4 hours a day and then lift some weight or body excercises and run. So more is better. If you can recover, so sleep and diet and stress levels. And the more you progress the more you can do. After 6 months you can do a lot of more volume then in the first 3 weeks. You do something more you get better at it. The number how much really just depends how much energy you have and time. And willingness to do it. It´s individual based on your current situation and shape.