Use of Listerine?

[akdb8r]

After getting a root planing at my last dental appointment, the hygeinist gave me a syringe and recommended that I fill it half with Listerine and half with water, then apply it directly to my gumline.

I've been doing this daily, but I was wondering: should I also rinse out my mouth with Listerine? Or would that be redundant with what I'm already doing?

 

[Gordon]

Seems bizarre advice in general actually, since the only thing in Listerine that really does anything useful is the high percentage of alcohol in it, why dilute it 50%?
How long are you supposed to keep doing this for?