To avoid chipping. A segmented rim's gaps mean each segment strikes the material as it re-enters, and that repeated impact chips a brittle glazed surface. A continuous rim stays in contact and cuts smoothly, which is what produces a clean edge on tile.

Only very briefly, and it is not advisable. Without gullets there is nothing to carry away heat and slurry, so the blade heats quickly, which can distort the core and damage the bond. These blades are designed for wet cutting and give both better life and a better edge that way.

Yes. Porcelain is much harder and denser than ceramic, and a general tile blade cuts it slowly and chips the edge. Porcelain blades use a finer diamond mesh and a bond suited to the density. Large-format porcelain slabs need blades specified for them again.

Feed slowly and let the blade do the work, keep water flowing over both faces of the cut, and support the tile fully so it cannot flex. Technique reduces chipping more than a blade upgrade does. Cutting with the glazed face up or down can also help depending on the saw.

A turbo rim has a serrated or waved profile that improves cooling and speed while remaining continuous, so it cuts faster than a plain continuous rim but chips slightly more. It suits cutting where speed matters and edges will be concealed; plain continuous rims give the cleanest edge.