listz practiced for 10hours a day. You need about 10,000hours of focused, correct and quality practice to be a master.
saying you practice 30mins of quality practice a day and justify it by saying it equates to 26hrs of practice is most silly unless your content to be mediocre

There is no such thing as a concert pianist who practices for 30mins a day

even the most talented pianist cannot pull this off without putting in the hours of hard work and sacrifices.
If your practicing your mistakes or just 'playing' your music, I doubt anyone would call that practice to begin with.