It confuses me

For the past couple of weeks I have been spending a lot of time with oils, over pastel and watercolor. I've been trying to improve my ability to paint nature in plein air, using photos, and sketches. So far it has been hit or miss. Occasionally I will have good days but most are mild or bad. That being said if I set up a simple still life I come away happy with the painting almost every time. I was having a hard time painting today. After three paintings of 2 rough and 1 decent paintings of natural scenes, I turned the light on this little pot and painted it on a 5x7 panel. While it is a little rough I'm happy with this for the time put in. If I can get this quick and decent with my nature scenes before the year is out I would be over joyed. At this point I'm not sure what the problem is. I think some self analysing is necessary to figure out what is stopping me from becoming more consistent, quick and better with my nature scenes. One thing is for certain, I do enjoy painting still life more every time.