If my dots are freshly up, annihilate is on cool down, and i have no need to build rage then I'll use it. PVE I'll use it somewhat frequently. PVP I'll only use it if the above parameters are met AND they aren't moving. My experience in PVP has been a full dot application+annihilate+full ravage will almost always be followed with vicious throw
In summary, if you can fit it in after you have dots up and annihilate is on cool down then by all means, do so.