Midi files contain song duration data, (certainly if you export them from Logic) unless it’s sysex, which could usefully define your patches numbers for you. Or just create a really short template for yourself.
In the UTool manual it says “the loaded MIDI file’s name will be displayed along with its duration.” and IM sure I’ve read somewhere in Cymatic user manuals that a song’s length is always defined by the length of the longest file, which seems logical.
So you dont need separate files for each song, you just need one tailored for your purpose, which must be as short as or shorter than your shortest song. Could be one second long.