You should use a strong password for your WordPress admin password.
A strong password is a minimum of 12 characters, using a combination of alphanumeric and ASCII characters.
Using only lower case letters limits the pool of possible characters to 26, so it is vital to include alphanumeric, upper-case letters and common ASCII characters to increase the pool of characters needed to crack the password to 92.
For example, here are the estimated times to crack a password using a four-core i5 processor:
- a 7-character password will take .29 milliseconds to crack.
- an 8-character password will take 5 hours to crack.
- a 9-character password will take 4 months to crack.
- a 10-character password will take 1 decade to crack
- a 12 character password will take 2 centuries to crack.
To conclude, use of a strong password is always recommend to safeguard from threat of getting hacked.