We have the same problem where I work too. Some like to take advantage of their autonomy and whenever a new admission is booked they claim to be overwhelmed and too busy to take another patient. These ones always take their breaks and have been seen at the desk reading books or knitting while the rest of us are scrambling to get stuff done and sometimes don't get breaks. They don't want to lift a finger to help in a crisis.
I tend to be a laissez-faire type when I'm in charge too - and I get put in charge a lot - my manager says I'm "a good egg". However, when I get report at the beginning of the shift, regardless of whether there are people who are going to try to take advantage of things, I write down everyone's names on the admit board whose assignment can handle an admission, in the order of who takes the first, second, third, etc admissions (for as many empty beds that we have available). This way it's fair to everyone and it's known right up front that they will be getting an admission.
Our institution uses a model of care that requires us to have an assigned Charge nurse and another nurse assigned to what is called Clinical Expert. The Clinical Expert's role is as a resource person and they are expected to field clinical situations, while the Charge Nurse's role is more of an adminstrative one. For instance, in a crisis situation, the Clinical Expert would be in the room with the patient, helping to start the IVs and delegating interventions, while the Charge Nurse would be the one on the phone contacting the physician, taking orders etc.
We also have a list of the delegated tasks that need to be done on the shift - I used to take it all on myself and do it all: BAD idea!! Now the list gets put up on the assignment board and when a task gets done, it gets checked off. Sometimes, people are not intentional "slackers", they just aren't sure what needs to be done, so having the list gives them something to do without having to ask them directly, and it gives them a chance to take initiative. I always make a point at the end of the shift to thank everyone for their help in making the shift go smoothly.
At the beginning of the shift, we pick a "partner" to cover us for breaks. I like to be partnered with someone who knows what it's like to be in charge, and has a similar style of leadership to mine. I tend to take my break earlier than others, so that there aren't a lot of people away from the nursing station when I'm on break.
Being in charge, I am supposed to have an appropriate assignment (a bit lighter) so that I am free to handle phone calls from Staffing or the Nursing Coordinator. It's best if my assignment can't accommodate another admission, but if I have to take an admission, I opt to take an earlier admission rather than one toward the end of the shift. That way, if there are people who tend to shy away from taking extra work, they don't have the excuse that I'm taking advantage of being in charge and not taking an admission. I also use the technology at our disposal to avoid unnecessary wasting time in meetings with other units - they want to know our bed situation at 5 am and the planned # of discharges - so I send each of the team leaders a message via the computer system (takes less than 5 minutes instead of 20 or more in a meeting). I use the extra time to make sure the assignment for the next shift is accurate and fair. And enjoy a cup of tea.