Nonono, it's totally okay ! c: Some people think brushes are 'cheating' and I disapprove of that. I'll dont even deny it, I use brushes, and I sometimes BRUSH THE F*CK OUT OF A TEXTURE to obtain what I want. :I
Therefore, the brush itself is never enough - it's better when you spend some time defining the forms on your own with some extra strokes and colors (like, on the trees, I did a lot of extra work on the leaves with the basic 5px brush on Photoshop to give a handmade feeling).
I can't remember well, maybe 3 hours or so... thank you so much qsfhsdkjs