You will never become full-time. CBS has adopted the American model of employment. You are scheduled for slightly under full-time hours so they avoid the benefits package. But you will always be expected to work overtime. The overtime will always put you over full-time hours, but that won't count because only scheduled hours count. Also you will not be paid overtime rates, just straight time. If they put out an appeal to the public for more blood more people will show up and you will have to work harder and longer. As a token of appreciation for all the hard work the employees provided the Company bought everyone a Hershey's chocolate bar.
CBS is chronically short-staffed because they can't retain employees (understandable). So everyone else has to work harder because the workload is the same regardless of how many staff show up to work. They won't hire extra staff in anticipation of employees taking sick-time or leaves without pay, even though that happens all the time and can certainly be anticipated based on historical evidence.
Nurses are being fired because Phlebotomists are being coerced and trained to fill their jobs at half the cost.
Receptionists are being fired and replaced with automated registration.
Phlebotomists are planned to be phased out with machines (although the early trials have pretty much ruled that out for a little while).
HR continually is out of touch with what is going on and what is needed. The staff do everything to make the place run better, and really do an amazing job and are the most dedicated people you'd ever want for employees, but they are thwarted at every turn by HR and the rest of the out-of-touch management team.
Don't even consider working for CBS.