I'm generally surprised when people don't . The few people I know who don't justify it with "I don't want to have to deal with all that support" (can't quite figure out what "all that support" covers). "When people have an issue, who do they call?" "Me" "So... they're already calling you. Why not have some $ for that to cover it". "I just tell them to call the hosting company". It baffles me how those folks stay in b…
I mean it's ok to include a week or two to fix bugs that you might have missed, but be up front about that window and make sure that you differentiate bugs with features. Clients might blur that line.