One of the things that comes up a lot as far as weed control goes is the landscape fabric. The fabric cloth that they sell, that you can put on the ground and then cover with balls or whatever for weed control. Not many are big fans of that stuff probably because they find them completely riddled with weeds over time.
If you put a nice thick layer of mulch on top of a landscape fabric, it will work perfectly for a while but then as that mulch breaks down, it turns into topsoil. Weed seeds blow in and they grow in the mulch through this fabric into the ground then you have an absolute problem. The point is, this stuff does not keep weeds at bay at least not for any length of time.
But if you can control external factors such as seeds blowing into mulch or birds dropping them off by either cleaning while they are sporadic or by placing some form of a barrier to prevent them from getting into your mulch. You have to pick a good quality weed barrier landscape fabric in order to have good results with weed control and if you can find a heavy duty landscape fabric then you would at least last you longer than usually expected.