In a reaction to Plan S, Highwire suggested that three of their society publishers make all author manuscripts freely available upon submission and state that they do not believe this practice has contributed to subscription decline. Therefore there is little evidence or justification supporting the need for embargo periods.
Highwire, in reaction to Plan S, suggested that three of their publishing societies should make all submitted manuscripts publicly accessible immediately, arguing that this has not led to a decrease in subscriptions. Therefore, there isn't much support for the need for embargo periods.