The best way for me to answer this question is with a simple analogy.
Think about your job, it doesn’t matter if it’s full time, part time, contract etc.
How many days a week do you work? How many of those days do you feel motivated to work?
Now, imagine for a second that the paycheck you get at the end of the month for your work (reflected based on how much you get paid per hour), is the same for the physical changes you see in your body and the abilities and skills you develop from the hours you put in the gym.
If you didn’t work, you wouldn’t get paid, right? But you work because you need money to be able to buy things to live.
This is the same concept with training, the more days you put into training, the more likely you are to see results, your ‘paycheck’ from the gym is the results you get from training.