3 things an artist make:
1. Finishing and finishing often. You should not be making the same thing all the time, but you should be consciously iterating in any direction you like as long as you are still finishing. Great painters, writers, musicians, are constantly making stuff, you only see the polished stuff that ends up through the filter.
2. Studying the great works in whatever your chosen field/style/genre. Know the "rules", the normal directions on the map, before you break them and decide on a shortcut or to buck convention all together. All great artists, even the enfant-terrible avant-garde artists, are extremely knowledgeable in art-history in their chosen field and can explain extremely precise opinions on the merits of one artist or movement. Most postures of naiveté are just that: posturing. Great artists know their stuff.
3. Surrounding yourself with other artists. You need people who will look at whatever you finish and tell you about it. Hopefully, these people should be as interested in good art as you, and as well versed or more well versed in art history as you. Engaging in communities of artists will make your imagination and creativity soar.
You absolutely need 1 and 2. You can get by without 3, but you will likely never achieve true greatness without it.
Everything else after that is luck.
1. Start often and finish often; do not be afraid to abandon something that is not working. Learning what is not working will come from starting and finishing more often over time, along with reflecting on the work you have done. This is where the benefits of #3 come into play. A good community will not only praise your work, they will tell when something isn't working or doesn't work.
The wasted hours are the hours that they are not working on the thing. One hundred hours is only a bit more than four days...and if you use both hands, barely more than two.
Or as Harry Truman opined. “If that’s art, I’m a Hottentotte.”
Once I had that done I could tackle stuff like “telling a story” which is a whole other kettle of fish.
Ask yourself what the shape of a finished larger thing is. How can you break it down into pieces about the same size as doing some of the drills you’re used to? What are the parts of it that require new kinds thinking and working? Make time to do that.
Take examples of stuff you want to be making and break it down. For instance I found it a useful comics-making exercise to take a short story by an artist I liked and write one sentence describing what happens on each page. That got me thinking about how much story could easily fit on one page.