In addition, it usally take about 8 days for your site to become fully distributed in the content network after changes. So, changing your keywords may adjust the 'theme' of your ad group, and so Google may re-evaluate your theme -- at that point, it would take about 8 days to be fully 'live.'
If I were you, I would e-mail support and ask them to increase your limit on keywords. I hear they do this on a case-by-case basis. But your account has to already be fully optimized (nice clean ad groups, organized by theme, and carefully selected ad groups).
If I were you I would download Google's "Maximum Effect" workbook and make sure your account follows their best practices before you make such a request.
I was aware it seems takes a week or two before a new AdGroup is assessed and properly running. What I've noticed is that REMOVING too many Keywords form an AdGroup that is running OK seems to put the AdGroup back in for reassessment.
So consider this...
if you find that one of your AdGroups is doing particularly well,
don't change anything!
What this means is that your ads are showing up on a "partner site" that's a good match for whatever it is your selling...
if you change your adgroup, you'll lose that good match as Google re-evaluates your "new" adgroup.
I lost a LOT of money back when I discovered this snafu...
One adgroup was pulling in $5k a day for almost a year,
paused the account inadvertantly one day, the next day it was all gone.
That was my very first adwords campaign, dumb luck at it's best.
I've never found anything as good since...
...and I wasn't tracking referrers back then. DOH!
It seems that just be removing Keywords that receive zero impressions affects the site performance.
Has anyone else noticed this?
This would be a new one to me, as a direct cause and effect relationship although I'll explore a bit further, since I've been surprised before. ;) The explanation proposed by RockSolidWes, as quoted below, could theoretically be at work.
So, changing your keywords may adjust the 'theme' of your ad group, and so Google may re-evaluate your theme -- at that point, it would take about 8 days to be fully 'live.'
On another subject:
If I were you I would download Google's "Maximum Effect" workbook and make sure your account follows their best practices before you make such a request.
I wasn't aware of Google's Maximum Effect Workbook - read it and learnt some more stuff (Hadn't realised I should use "Online" in my Ad Healines and didn't know that they disabled any Ad not delivering at least 0.5% click through - after how long I wonder?)
This document, while excellent in it's time, is outdated. The information quoted just above has not been correct for a year or so. Please tell me you aren't finding this doc anywhere in the AdWords Help Center. ;)
AWA
What parts of it are out of date? Is there something up to date I should be reading?
I'm just about to start work addressing all my AdGroups with a CTR below 0.5% - is this still valid?
Check out section 3, sub-section a of the 'adwords learning center' videos. And entire section 6.
I'm not AWA, but I hope those sections help you.
