The key to understanding why tIS is a better choice is to reframe the way you’re thinking about your strategy. If, for example, you’re wanting to use Max Clicks on a campaign that is targeting your branded terms, then it makes sense to think that you want as many of those clicks as possible. However, due to the aggressive nature of Max Clicks, this often ends up being a very inefficient approach.
It’s also common to find that your Impression Share is actually much lower than what you want for the terms you’re going after. If Max Clicks overpays on the first few clicks in the morning, then you’re out of the running for the rest of the day.
If you reframe it as, “I want to show up for at least 90% of my brand searches, but I want to keep my CPCs within reason.” then you start to see why tIS might be a better fit for capturing high-value traffic or playing defense on your own brand.
Target Impression Share lets you control the percentage of searches you want to show up for, and the Max CPC that you’re willing to pay. This gives you another control mechanism that tells Google not to blow your budget on the first few clicks. I don’t mean to personify the bidding strategies too much, but that seems to help taper Google’s aggressiveness in the ad auctions, and makes your budget go further.