I know that on high-speed transmission lines you should not route with "sharp corners". I thought this meant no 90 degree bends. But "accordion" traces commonly used for length matching are essentially multiple 180 degree bends. (Admitedly, the corners in an accordion are typically rounded arcs rather than sharp 90 degree angles, so that may be a huge factor.)
So are there any rules of thumb about how to space accordions? How tight is too tight? In the image below, the yellow accordion is a .2mm trace, spaced .5mm senter to center. (.3mm gap). Is this fine for an SDRAM memory bus?