how long do those typical ice cream makers with the core that you freeze tend to last? Specifically, I was wondering if the freezer core loses efficacy over time (in particular as I store it in the freezer). I wouldn't have thought so, but I feel like it hasn't been as effective lately, though perhaps it's just the recipes I've been using. (I've been making the Jeni's recipe but have now been trying ones with the more traditional egg-yolk base thickener, though I wouldn't have thought that mattered). I'd love the answer to be that I should get one of those compressor ice cream machines but then I see the price!