While I think videos that're short are acceptable within the ASMR community. I think longer videos is something you should be striving to have in the future as you're competing with ASMR channels who do quality ASMR with the same triggers and longer videos so you need to find a way to standout amongst the crowd and few people watch shorter videos because they want something they can zone out too while studying, or sleeping too and in some occasions can use as therapeutic sessions.