I've worked in a couple of Level II NICUs. Both had in-house neonatologist coverage during typical "business" hours and for pre-arranged events such as planned sections of multiples, deliveries of babies with known conditions, etc.
Other hours were covered either by NNPs, local pediatricians or fellows from a near-by children's hospital, with the neonatologist on back-up from home. They rarely needed to be called in at odd hours, but were responsive when the need arose.
So there was always a capable medical caregiver in house, but their credentials varied.