The idiosyncracies of vTaskDelay(1) are part of RTOS folklore (not specific to FreeRTOS, btw) and are documented in many many places. An attempt to include this in the official docs has been made here: vTaskDelay… documentation update? - Kernel - FreeRTOS Community Forums but unfortunately, the page linked to has disapperead. @kstribrn : What is the status there?
Thanks!