Having experience in both primary and team nursing, I would not accept a team position again. Disclaimer: the hospital in which I practiced team nursing was quite possibly the worst on earth, and the hospital in which I practiced primary was among the best, so my opinions are admittedly slanted.
First my primary nursing experience. A large Level III NICU in a teaching/referral center. We cared for babies for months at a time, often transported from a distance with parents unable to visit on a regular basis. We also had residents who rotated thru our unit on a monthly basis, so our babies needed consistent advocates in the form of nurses who were well-versed in their needs and care. We worked a combination of 8 and 12 hour shifts, and would be assigned to our primary if at all possible, sometimes as a single assignment (when they were critical), and sometimes with 2-4 other patients as they improved and became feeder-growers. The idea was to have a primary nurse on one shift and "associate nurses" on the other shifts so that there was someone at least once a day caring for the baby with intricate knowledge of the child's needs, who would update the care plan, round with the physicians, suggest treatment options and consultations, communicate with PT, OT, social work, discharge planning, plan and provide parent teaching, etc. It was extremely satisfying to follow a baby from admission to discharge, both for the nursing staff and family.
Now the team nursing unit. It was a post-partum unit with a separately staffed newborn nursery. We all worked 8 hour shifts. On any given shift, the mother would see her RN who did assessments and managed IVs, her LPN who passed meds and did treatments, her CNA who took vs and assisted with ambulation, hygiene and linen changes on stable PP moms, a bath tech who did baths only on fresh post op C-section moms, a dietary aide who passed trays, a nursery nurse who cared for the infant and provided infant care teaching, and a lactation nurse who assisted with breastfeeding. That was 6-7 caregivers on every single shift. As a result, care was terribly fragmented. Hours often passed before news of an elevated temp or B/P made it from the CNA to the PP RN to the nursery RN, meaning that babies were left with moms who were unstable, and/or the nursery RNs were unaware of conditions that warranted septic work ups and isolation of infants. Teaching was haphazard, and often left undone until the last minute when the discharging nurses had to cram it all in.
Neither system has a lock on good vs bad. In any situation, staffing ratios must be appropriate to patient care needs. 6 patients to 1 nurse is too many, even with LPNs and CNAs. In a primary nursing situation caring for heavily dependent patients, I think 3 would be the max.