haha don't worry, we ALL feel this way but we can only do what we can with the time that is alloted to us. some may have more or less free time than us or some may be at it longer than us to be good enough to make fancy art quickly. you'll get to where you want to be one day
I used to be like that.... until i figured out how to use em properly..
imo on sketches I use thicc lines. then once i have the sketch down and im ready to painstakingly carve the lineart, then I use the thin lines.
Imo thin lines have their place. tho lineart can be one of the most infuriating parts of drawing cuz it takes the longest (esp if doing an animation XD) but i'm always super happy to get to the coloring cus thats my fav part. i'd say lineart is half the battle - at least for me anyways - but if you practice em you'll def get better!