I've only seen 12 word pass phrases  mentioned in what I've read so far, but as a noob I am less than a week into this .... new hobby I guess.
Today I installed the coinami wallet app on an andriod phone, it created an 18 word phrase ....  how significant is that? I assume if makes the crypto even stronger but maybe beyond necessity?  Also since most other wallets only use 12 words wouldn't there be a compatibility issue if you wanted to change wallets?