Should I use the same username on every site?

[AmandaNerdBot]

I use this username on most sites I post on. I occasionally use a different username, but I generally use this username on most sites I post on. Is that a good idea?

[Hideki Motosuwa.]

That shouldn't be a problem. It's a good idea to use different passwords though. I use the same base user name on different sites, but I end up putting a different set of numbers at the end of the name. No real meaning, but it's good fun.

[GameGeeks]

^Pretty much that. I've been using this name since 2005/6 with no issues.

[Sympathy]

what issues could possibly arise from using the same username on different sites? why do you even need to ask about this?