Meditation is a lot like jogging to lose a lot of fat.
If you jog only when you feel inspired, you are less likely to lose fat or even build up your wind. If you job regularly you will build up wind, be able to job more, burn up more fat and alter your metabolism.
It works the same way with meditation. If you do it consistently everyday you will find it easier to focus & your stress reflexes will change. You will find yourself responding to stress more quickly, but also powering down from stress more quickly.
It is better to focus on the habit of doing it every day rather than doing longer sits.
A good way to start is to pick the same time every day to do it. For example, after dinner when your day is done. Another example might be before you go to sleep, as there is always a "before you go to sleep" no matter how hectic your day is. If my day doesn't 12:30 AM I just tell myself "my day, unfortunately, didn't end to 1:30 am, so let me meditate now at 12:30 am ".
In reading the scriptures, there are two kinds of mistakes:
One mistake is to cling to the literal text and miss the inner principles.
The second mistake is to recognize the principles but not apply them to your own mind, so that you waste time and just make them into causes of entanglement.