Should IP address be Blocked?

[Maynards]

For a few years I have been blocking IP address through my control panel. They have been blocked because they have been using my site in various way's and are from countries like the Philippines which I do not do business with.
I just realized that IP address can change on computers. (my computer has a different IP address as of the last few weeks) Since IP addresses can change should I be blocking them?

[kobra]

Really a futile operation as hackers can use mulitple IP addresses