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It does depend on the finish of your worktops but they are normally factory sanded smooth and oiled or varnished. Different woods have different grain patterns and some types of wood vary considerably depending on the tree they came from. The factory will probably plane the surface flat and then sand from a heavy grit through to a fine grit on large band sanders, the output is monitored to ensure an acceptably flat surface.

When you sand your worktop you are essentially scratching the surface off and the scratching pattern left on the surface is pretty obvious at 80 grit, if you then move through grits 80, 150, 280, 350, 400 you will have a surface that most people would consider smooth. However depending on the mode of operation of the sander you will have introduced some scratches that are not obliterated by the next higher grit in a pattern that is obvious to an experienced eye.

For example a random orbital sander will leave random semi circular marks from the lower grit which doesn't get erased by the higher grits. A rotary sander is a little better but it's very aggressive at lower grits, it's a decent compromise but expensive. A linear sander worked in the direction of the grain is great on a close grain wood, but on a softer more open grain will strip out the softer wood between the more sinuous grain.

If you restore furniture which requires a high gloss you have to take care of a lot of these problems and in great detail. In this case you would apply a chemical stripper and use a scraper to remove the existing oil/varnish then apply a grain filler and possibly dye to colour the wood before applying the oil/varnish. If you sand a mahogany top it's incredibly difficult to get rid of sander marks as the grain shows so clearly under the gloss.

tldr Take it from an experienced professional, chemical stripping is the premium option. It can also remove burn marks and stains without having to sand the whole surface back.