3-seater leather sofas

Shoulda swapped them around a few times then....

Why would they, you will probably sit in the same place on the sofa as you feel comfortable there. The flattening will still be there courtesy of whoever sits there the most.

A 2 cushion 3 seater makes it more uncomfortable for the poor unfortunate person in the middle. Then again if you don't actually have 3 people on it very much it won't matter.

Get one where you can change the filling.

The cushions aren't detached!

Nope, we never do.

I'm not sure theres an answer to this as we have recently looks at buying a new sofa and it would appear that most (if not all) leather suites don't have removeable cushions and therefore the one's which get sat on the most will sag compared to the others.

Never seen a leather sofa with changeable filling!

The cushion covers may not have zips but it shouldn't be impossible to open a seam and replace the pad.

In extremis, find a vet experienced in bovine caesarians.

Owain

Change around, if you can-- which you can't if the front outside corner is L-shaped. When you're thinking of being able to change the cushions around on the new sofa--back to front, top to bottom--look for square-shaped when you're shopping. Cheaper sofas--Ikea et al.--frequently have the "good" fabric (in your case, leather) only on the top side. Look out for that, too.

But you didn't say what the filling was. The inside life of cushions will determine how long the cushion keeps its shape. Ikea uses "country feathers," which I suspect are chicken feathers. I personally stay away from any feather or down fillings since I can't bear the smell, especially as the cushions can take on quite a gamey odor-- on moist days especially.

There are various types of foam cushions, and the best kinds are expensive: on sofas these are usually formed; loose foam remnants in a cushion shout cheap-o. Foam, even the expensive kind, can get crumbly, just like foam mattresses. We bought an expensive bed-sofa in 1970, covered with a sturdy fabric; over 2 meters long, it has a one-piece seat surface and three flat back cushions. The cushions are at the crumbly stage by now, but the seat and arm rests are still very good. I cover it with white Ikea cotton throws and exchange the one on the seating surface weekly (I have three Dandies).