Wasted paint isn’t wasted if it taught you what not to do next time.

Materials you used up learning are not the same as materials you threw away. Every ruined canvas narrows the field. Now you know that combination goes muddy, that this brush cannot hold that edge, that the second coat was a mistake. Nobody can hand you that in a lesson, because your own hands have to find it, and from outside the work it just looks like mess.

Keep the failed one where you can see it instead of binning it. Write one line on the back about what went wrong, and read it before you start the next.