The scanner's "main memory" can hold 1,852 objects. Those "objects" are Conventional channels, Talkgroups, Trunking systems, and Search/Sweeper settings. (CONV and TGRP each take one "object space", the other types take more).
Any object can belong to zero, one, two, ..., 21, 22 scan lists, without impacting memory usage. So, a Scan List can "hold" 1,852 conventional channels (if that's all you had in the radio), 1,842 TGRPs for a single P25 TSYS, 1,000 Conventional channels plus 842 TGRPs for a single P25 TSYS, etc.