https://www.theregister.co.uk/2018/06/11/ibm_to_gts_we_want_you_to_rotate_clients_every_2_years/

Exclusive IBM will ask Global Technology Services engineers to "rotate" from "existing assignments" every two years in a working model overhaul that some staff warned could weaken client relations.

Under the current setup, IBMers working in the field can transfer to different projects or work across multiple accounts but they generally tend to have a "home" account where they spend much of the time.