Do you all have a basic guiding rule on cap voltage?

Recently, I had more then usual failures in my builds. After some digging I discovered that I got a bad pack of caps. Many of them were upwards of 40% off what they were marked. I have never had that happen, but I'm not super surprised, it was a new vendor and pretty cheap. But this all got me thinking and questioning everything. Do you all have a basic guiding rule on cap voltage? Generally speaking when I see a layout I will typically us 25v caps or just basic film caps but it's not uncommon to find BOMs asking for 63v caps. Without pulling out a calculator (I know, that I should and I do when it's required. When i do the math my general rule is volatge = 2x voltage of circut) what voltage caps do you generally use?

Note: A lot of this question is based in my endless hours of looking up PCB and strip board layouts and cross referencing them with left over parts or just judging complexity of build. Most layouts don't have specified voltages for caps. I am wondering if my use of low (25v when it should have been more but not specified) voltage caps might have added to failures in the past.