Do different mushrooms grow at different rates? You bet! And yes, it depends on what you are looking for..........Even more importantly they might change a lot for other reasons besides rain; a pefect bolete one day is a production factory riddle with bugs the next. An Inky cap that one day is perfect can be an unidentifiable mass of black slim the next. Then there is those pesky slow growers such as hedgehogs that seem to take weeks to have any identifiable growth. Freezing at night can also make many mushrooms turn to a glutinous mass. So if you have freezing weather at night, go the day before. Here in the PNW, the chanterelles can be very eatable for weeks during late summer when they grow particularly slow when there is a lack of rain.........then those that come up with a rain will be good but can be a bit watery........then the freeze hits. Good luck. Great question!