I don't have a source, but most capital deployed by private investment firms (ie, the firms where the exemption is relevant) is deployed by traditional PE shops. And in my direct experience, the employees at traditional PE shops who invest via the exemption are almost always associates. And also in my direct experience, the vast majority of PE associates are on the job for two years, three max.

Private equity associates very rarely receive carry, which is why they co-invest instead.

*edited for clarity