How long are cusps?

Say if you were born on the Aries/Taurus cusp, April 20th. How exactly long are the cusps? I looked on a website and it said that the cusps are five days before and five days after. I'm not sure if it's true, but I want to hear your thoughts on it.

I personally like looking at cusps by degrees. There was a post I saw soon after I joined this site that listed the degrees of a cusp. Here's the link for that topic:
https://www.dxpnet.com/opinion/zodiac-cusps/how-do-you-know-if-your-moon-or-rising-is-cusp-1042809/
From what I can gather from other sites, not all cusps are the same length. Yet it seems hard for everyone to agree on when the cusps should be. I've taken it for fact, for example that the aqua-pisces cusp ends the 22nd, yet some say it ends the 23rd, which would mean I'm a cusper.

I don't know what everyone else follows, but I'm going to follow what the link I posted suggests.