Charge Therapist Duties?

I am fairly new to a facility (have been here ~8 months) and I have never worked anywhere where there is a charge therapist at such a small facility.

I have worked at an 800+ hospital and there was a lead therapist and this RT did not have an assignment but spent the shift checking on others in their assignments, doing transports, going to rapids, would make the shift assignment, handle issues that come up during shift, etc. I’ve worked at a couple other hospitals as a traveler so did not have too many worries about being charge.

The current facility I’m at is ~180 beds and staffs 3 therapists a shift. 1 of these therapists is assigned to be charge therapist (with an assignment as well) which is made out on the schedule by the RT supervisor. Since I have been here, on weekends I have noticed if there is a call out the manager has asked the charge RT to find coverage for said call out. Is this normal? In a larger hospital like I was at before, a call out didn’t really impact the assignments but here it makes a huge difference. And then depending on the count, day shift is expected to do some of nights 1st rounds to help out. Just curious how other facilities operate.