I've upvoted in agreement but it does depend on whether you are ready to leave (I seem to get itchy feet after about 5 years even with some internal variation), are really happy where you are and what you see as the risk profile of the existing job (cuts/relocation/new boss expected). So the absolute figure needs to be flexible for non-financial considerations and may go negative in some circumstances.

If the only reason to move is the money then for me it would take more like 30% to take the risk.

Agreed. I had an old manager that said that 10% is the bare minimum, just to cover the change of job risk.