By using a wildcard, one user can be granted privileges that are valid over several locations in the same network.
\!h Example - allow 'jill' to connect from any of the machines in the domain invyhome.com:
GRANT ALL ON *.* TO 'jill'@'%.invyhome.com' IDENTIFIED BY 'password';
-- the same can be done for the IP equivalent:
GRANT ALL ON *.* TO 'jill'@'192.168.1.%' IDENTIFIED BY 'password';