this is a difficulty for people who go straight from undergrad to PhD. It can also be a slight warning sign (but absolutely not always) if a phd grad has no experience at all, because usually phd students need to supplement their scholarship/RTP, and supportive supervisors will give good students a boost with some casual work to give them experience/time on the books.

But yes - I often encourage students to get some experience, one way or another, while studying. Often, the type who go straight from one degree to the next are precisely the type who worry that taking a few hours out to do paid work each week will negatively impact their academic performance, etc, and they need to be gently reminded that a well rounded application is stronger than a straight H1 student who has never seen or done anything!