Let say you create the following numbered extended access-list:
access-list 123 permit tcp any any eq www
access-list 123 permit udp any any eq 54
access-list 123 permit tcp any any eq smtp
access-list 123 permit tcp any any eq pop3
access-list 123 permit udp any any eq syslog
As you type in the last line you release you made a typo, by entering UDP-54 instead of UDP-53. This is likely why most of us prefer using Named-ACL’s, because without sequence numbers in the ACL you can not remove that one entry, you have to remove the whole ACL. Although Named-ACL’s are handy, there are still times when you have to use a Numbered-ACL.