Do you tear down or change tanks regularly?

I was wondering if any members regularly tear down/change their tanks? I know some of our planted members will completely change the look and feel of their tank, possibly by changing substrates, plant choices, and fish selection. I can see how it could be an appealing thing, particularly with multiple tanks. I always enjoy having a project with my tank, adding something new, or moving things around. I don't however usually make large changes in aquascaping as I probably could. I have had a couple of major changes in layout with substrate changes over the years, but never anything larger than that.

So a few questions:

How often do you change your tanks?
What do you change in them?
Why do you change them?

That's an easy one,

Other then my two saltwater aquariums, there is nothing in my tanks other then fish

So no I never tear down my tanks.

Steve

Interesting.
The only time I change substrates and rocks would be when I change geography - if I have a tank of Mexican fish with a mineral releasing substrate and want it to become a West African biotope with softwater, the substrate has to go.
With the luxury of many tanks, I have some that have had the same substrate and plants for 10 years.
I change fish species regularly, but 90% of my plants come from a buying spree of about 3 club auctions in the early 1990s. The carefully chosen and expensive at the time low light plants did well, spread, and now fill most of my tanks.

When I have a fish that hasn't become a favourite but that I feel I have learned what I want to from, I take it or it and its young to the local auctions, and let someone else get a crack at keeping it. In return, I get money for food, or for new species to learn about.

Sometimes a fish grows on me, my boesemani are taking more and more place. I'm always trying new breeding tricks or set ups, and I'll redo a tank for that, sometimes.

I make changes both small and large. I will make small changes such as switching out a plant for what reason it maybe whenever the need arrives. Fish species in tanks do not move to often but only if I switch out a species completely. I will do larger changes such as a entire rescape or substrate change ever year and half or so. I do sometimes because the substrate might need to be changed out for a planted tank. But most of the time I do it because I like change and to keep my aqua scaping skills fresh and being creative. Setting up a scape with new and challenging ideas and figuring out layout for plants, rocks, and driftwood is something I really enjoy. But some tanks with slow growing plants with remain for years or if I really like a layout I have done. At the same time I have to keep the tanks functional for fish breeding as well. Makes for some great challenges.