I keep a sand bed. Started out 3", but now is various. I hardly ever touch it, but about every 4 years, I vacuum it out in 20% increments with a month or two between sections to allow everything to settle. I love the anoxic areas for bacteria to complete the nitrogen cycle and turn no3 into nitrogen gas. I love that it will buffer phosphate for me so that I can never get too low. I love the critters, cucumbers and sand-sleeping wrasses - the critters and cucumbers do required lower N and P than most people have anymore. I love that mature sand don't allow a fertile breeding ground for fish parasites and any ich tomont that hits my sand has to fight for it's life from a litany of creatures wanting a meal - don't underestimate this.
I am a huge proponent of sand and really appreciate what Dr. Ron did for the hobby. The one thing that I think that he got wrong was not dealing with the glut of benign materials left over that settle in down there. This stuff is not a nutrient sink or anything like that, but it does gum up the works and keeps cucumbers from doing their jobs, water flowing freely to deeper areas, etc. I like to get it out ever 4, or so years.
Once I vacuum a section, the sand snails, cucumbers and everything spends more time in that area for a while. You have to go slow so that the oxic and anoxic areas that you disturbed can establish again before you move on.
Everything that you hear about sand being time bomb or any other useless and incorrect internet slang is all a result of poor husbandry. The sand can help you out for a long time, but eventually it cannot do it's job anymore and you have to pay the bill down the road.
I document more of my methodologies and techniques in my rebuild thread.