Extensions & reductions ?

[MahmoudUthman]

Should I extend moves "that should be extended eg: Checks " that I don't reduce , or is not reducing them enough ?
For example I extend checks by 1 ply , If I don't reduce checks in LMR should I use depth-1 or depth+extension-1 or depth-reduction+extension ?

another non related thing : what advantage does fractional extensions have over integral ones , if any ?
& should you extend checks at root ?

[jdart]

For most of these questions, there is no substitute for testing.

I have noticed quite a few engines (for example Stockfish) now use only integral extensions, after having previously tried fractional. But your mileage may vary.

--Jon