I've got a great recipe for chili. It takes about 10 items, but if I send you to the store and you only return and give me 5 of them to make my chili... it's not going to work.
In terms of the economy and "Obama's policies," we don't know if they'd work, because they are part of a recipe that included both spending cuts (yes, cuts) and a return to the taxes of the Clinton administration (in an era when both sides still worked together, and the economy freaking thrived). The republicans allowed the cuts, but not getting rid of the failed Bush tax cuts. So, it's a recipe with half of the ingredients missing.
The economy and job situation are getting a little better even so... but I believe they would have worked faster without Republican obstructionism. So, when Republicans say "his policies" aren't working or aren't working fast enough... it's because they didn't allow "his policies."