I use an eye shadow primer sometimes and it definitely helps making it last longer/minimizes fallout. But this is not an issue unless I have really long days or if I have some kind of event to attend and I want to make sure that the makeup stays on no matter what happens.
I haven't worn eyeshadow in years because it always wore off but now I use it again with an eyeshadow primer and it makes a big difference! I also use a face primer once in awhile because I normally use moisturizer but primer works awesome too. Its worth the money if you use makeup every day or every other day. My sister has all this expensive makeup and primers and wears makeup once or twice a week and I think "what was the point in buying all that?"