Don't get soft flabby boy.

There's this irrational fear put into classically minded artists, I don't know if it happens directly, not always, or we just absorb it via osmosis from the rigidity of the method, but across the board one of the common fears I've noticed talking to friends, and ones I face personally, is that you will grow weak or get soft from only working with references, or going any length of time not working with the figure directly from nature.

Frazetta must have gotten all of his cro-magnon  friends
to model for him in this easy to hold action scene...

Whenever I have this fear I stop myself and think about how many artists who I admire who worked from photo's and out of there heads alongside working from nature, and who I still can't even touch in skill.

It's not whether or not you use references that will lessen your drawing skills, you can't let that fear eat you because it does nothing to help you become a better artist, aaaaand it's not true. Using photo's won't inherently lessen your skills, but what will hold you back is a lack of discipline and ability to creatively solve problems as you come across them in making pictures.

So long as you are practicing you will be gaining skill. Repeat that over and over to yourself, the act of painting and the desire to do better than you did last time at all costs whether it's from life, references, out of your head or in another dimension, it doesn't matter, just paint and you will get better. The more important thing is that you don't get stuck being able to only work one way, the longest and hardest road to be on is the one where you are the most versatile, if trying it one way doesn't work, you let it go and approach it in another way no matter what anyone has told you is the supposed "right way" to do it.

I think about making art as I would having infinite resources to go exploring in a hypothetical world where there aren't so many people everywhere, always be asking "what if," especially if you get stuck, but if the inclination strikes you to try something different, give in, you will only gain from it.