I'll echo what others have said. Takes multiple sessons. My 2 o'clock shadow was horrible before i started lasers. I went through a series of 8 sessions at one place with very good results on the neck and cheeks. Those two spots are almost clean now. The chin, lips and mustache for me are much tougher and more painful. The old place i went to is out of business so i'm at a new place now. Each time it gets better, but the lips and nose area are always painful form.
Scheduling:
1. I have heard that it is more painful in the mornings when the skin is fresh. So I've always schedule mine for the evenings.
2. I also usually schedule for later in the week (Thursday or Friday). See shaving comment below for rationale.
3. Both places i've been to recommend spreading the sessions 6-8 weeks apart.
Before each session:
1. My skin is pale and hairs are dark / dense. So i shave the morning of the appointment, then again a few hours before the appointment.
2. Sometimes I use the ibuprofin an hour or so ahead of time. It seems to help, but it might just be in my mind.
After each session:
1. You could try some non-alcohol based soothing sunburn cream / spray to use for a few days after each session. That seems to help my skin recover (and feels wonderful).
2. Putting an ice bag on the area immediately after each laser session. This helps to minimize swelling. But i don't leave it on my the artery on my neck for too long because i get woozy

3. I also don't shave for a day or two afterward due to sensitivity of my skin, swelling etc. after each laser session. This is why I schedule my session for late in the week, so i don't have to good to work looking unshaven.
Lastly, Not sure if others notice this as well. On some parts of my face/beard, it just gradually decreases the amount of hairs uniformally

. But on some spots like my neck, i noticed after one session that i had several small hairless spots.

Then in the next sesssion i saw fantastics results

like all the bare spots connected and all the hairs dissappeared in between. Smooth like a baby's bottom.
Now I have some small bare dots on my chin... and i'm eagerly looking forward to my next session to see if it will yield fatastic results for the rest of the chin area.
Obviously not scientific, but the patchiness seems to be a good omen for me.