Can I use the subliminal messages in short length audios?

I have downloaded this software for adding own subliminal messages to the audio, but they have suggested this long long audios as background music( 30 mins, 60 mins and so on) which are computer generated music, or sound of nature,or relaxing type of music. so i am confused if it works or not if i use those subliminal messages on short audios like the songs i generally listen to ( 3 mins, 5 mins).Does it take some time for those messages to be recieved by our subconscious mind??