Question

What happens to a capacitor when we use 2, 3, or 4 times RC time constant rather than 5 times constant? What it's effect? Does it become dangerous?

Answer 1

Actually, the time constant is the consequence of RC, not the reason. But if you try to charge a capacitor with some high-power source "using 2, 3, 4 times RC", then it may blow up and you may get burns.