You can change the amount of time an IP is locked out for using a bad login name in the options. Login Security Options - Amount of time a user is locked out.
For example, I have one site where I am the the only user, so I use the following:
- Enforce strong passwords? - Force all members to use strong passwords
- Lock out after how many login failures - 3
- Lock out after how many forgot password attempts - 3
- Count failures over what time period - 10 minutes
- Amount of time a user is locked out - 60 days
- Immediately lock out invalid usernames - true
- Don't let WordPress reveal valid users in login errors - true
- Prevent users registering 'admin' username if it doesn't exist - true
On another site where I do have users, I use the following:
- Enforce strong passwords? - Force all members to use strong passwords
- Lock out after how many login failures - 3
- Lock out after how many forgot password attempts - 5
- Count failures over what time period - 10 minutes
- Amount of time a user is locked out - 10 minutes
- Immediately lock out invalid usernames - false
- Don't let WordPress reveal valid users in login errors - true
- Prevent users registering 'admin' username if it doesn't exist - true
Hope that helps!