Definitely.
Always intonate with brand new strings.

As far as how often to change, it kinda depends on what you're using your guitar for.

When I'm playing live I change them every night (saves me the worry of having a string break in the middle of a song)

In the studio just for general everyday rehearsals or messing around I'll just leave them on until one breaks then change them all.

If I'm recording a new song or doing a bunch of Guitar Tricks videos, I'll put on new ones get the best sound. I'll also clean the fretboard and use a little lemon oil on it because my guitar's over 30 years old and majorly drying out.