Transfer switches at any facility that's worth being colocated in are exercised as periodically as the generators to which they connect. In all of the faciliti

Transfer switches at any facility that's worth being colocated in are exercised as periodically as the generators to which they connect. In all of the facilities I have had systems in (>20MW total steady state IT load), that meant once per month at minimum to keep generators happy -and to ensure the transfer functionality works-, and more often if the local grid demands it, e.g. ComEd in Chicago, or Dominion in NoVA asking for load shedding.