Excellent advice. I was helping manage an Adwords campaign for an online shop, only had search ads turned on, was carefully watching and tweaking ads and managed to get a pretty decent CTR which had a big impact on cost per click.

I was in a different time zone (15 hours ahead) than the company. I went to bed one night and next morning I checked and found that our CTR had gone through the floor, was way less than 1%. And as a result our cost per click had sky rocketed from 10 to 15 cents to several dollars.

Turns out that a Google ads rep had called the office and convinced someone to turn on display ads, which killed our CTR. Our advertising budget was depleted, our Adwords account had received the dreaded low CTR slap which meant it would be very costly/impossible to get CTR back to a reasonable level. We were done with Adwords.

Things may have changed since then. It was years ago and I haven't touched Adwords since.