Comment by buescher

Yeah, in the typical value ranges (nanofarads) of a 555-timer-class analog design, you'll need film caps. Ceramic C0Gs are too small and class 2 dielectrics are dismal for anything but bypass. They don't just have temperature coefficients, they have voltage coefficients and are wildly nonlinear. And electrolytics are almost as dreadful as batteries. Worse in some ways. It's a tough bridge for beginners to cross - once you figure out capacitors are not all equivalent you have to do a deep dive on dielectrics and it's a bit of a chicken-and-egg problem - you don't know what you're doing so you don't when you'll need what.