While this type of medium should last longer than your average silt based mixture, you will need to repot or refresh it from time to time. That will probably depend on variables, such as how long it takes the fir bark to degrade in your climate and environment, what type of plant, size of pot and plant, etc.

I'm sure Tapla can elaborate, and explain better than I.

I grow Amaryllis bulbs and a few other plants in relatively small pots, all of them unglazed clay, and I probably renew my gritty mix once every 2-3 years, or thereabouts.

If you want to do the work, you can sift out the reusable stone... granite chips or whatever you use... but I get a second life out of it by dumping it in my raised beds to help with aeration. I don't use a ton of the ingredients, so it's not a huge expense for me to purchase new ingredients every few years.

Hope this helps. Don't forget to check the roots for needed pruning while you have them out of the pots for repotting into fresh medium. :-)