Different people feel comfortable with different amounts of work or study and other commitments.
Some people prefer more or fewer hours in these pursuits than others – one size doesn’t fit all. Sometimes you have control over how your time is divided. Other times, you might have to sacrifice social commitments to get study done, or work more hours than you’d prefer, to make ends meet.
Having balance is about understanding your personal ‘sweet spot’ about whether you are working/studying too much or too little. (Everybody makes these judgments for themselves within reason, because we’ve all got bills to pay.) Doing too much can lead to burnout and anxiety. Doing too little can lead to boredom and even depression.