Actually just one.
I started with a fish-in cycle as I had fish before I had a tank. The fairground goldfish spent their first night in our home in one of my cooking bowls in non-dechlorinated water. For 10 years after that we had only dial up internet so I no idea that there was such a thing as cycling so if I upgraded a filter I just swapped it
Once we got broadband I started reading up on new ideas and discovered cycling. So if I set up a new tank or got a new filter after this I used mature media.
Then I had a betta which died from what I thought was lymphocystis which had got into his gills (I now know it was a tumour) so I threw away the media, sterilised everything else with bleach, then thought I would give this new cycling method a go to see what it was like.