You're not getting old or forgetful, there is a reference to only being able to trigger one preparation per Combat Turn in the Street Grimoire, pg 210; red sidebar, third bullet-point.
However, the sidebar is (supposedly) a rules clarification, and it even references the pages for the preparation rules in the CRB. It doesn't seem to be intended as a rules change, so this otherwise non-existent limitation to one per CT, is widely regarded as an error. Perhaps they meant one per Action Phase (per Pass, instead of per Turn). But yes, the more important limitation is the attack actions. As a GM I would urge that to be the primary limiting factor.