What about old wasted gritty mixes(ones that turned to almost mud)?

Or very compacted ones?

I avoid disturbing Astrophytums and Melocacti rootballs if possible. If a plant has a tightly packed rootball, I will break it apart with force otherwise simply repotting it in a larger pot means the roots won't penetrate outside the rootball and little growth occurs. A tight rootball will also have a lot of dead roots within it.

milevskistefan - I find gritty mixes - that many of the more experienced growers prefer - do not turn to mud - mud needs fine particles. For the same reason they do not become very compacted.

And ´tightly packed´ rootballs tend to occur when a plant has become totally pot bound - generally through neglect. My EXPERIENCE is that when such a rootball is surrounded by fresh soil the roots avidly grow into the fresh soil and a rather increased growth occurs - totally the opposite of what s g thinks might be the case.

Spanish fly, ive only recently achieved what you can call a proper gritty mix, id rather call the old ones mimicry(cause they did work after all). That being said, ive avoid repotting some plants for that very reason- i feared that a bad mix will be detrimental to my older plants.

As Spanish fly said...