Having multiple ad groups means the budget might be split unevenly between different ad groups and you’ll have no control over the budget. With Amazon, you cannot set an ad group-level budget. You can only set it at the campaign level.
5 keywords maximum per ad group is recommended. If you push the limits to 10 for example, you will find the top five are getting most of the spend, and the bottom five will slowly get less. Even beyond 10 with a huge budget of $10,000 a day, you’re going to notice that all of the budget is going to the top five keywords
For example, if you have a campaign with five ad groups and your campaign daily budget is $100 a day, each ad group would theoretically get $20 a day. However, as you don’t have control over how much money Amazon’s going to send to the different ad groups, you could have a $100 campaign budget, and it might send $90 to one ad group and then $3 to the other ad groups and then maybe nothing to the last ad group.
To find these keywords go into your ad group and sort by spend, then scroll through the keywords. Look for keywords where you notice slow impressions or no spend, or maybe over the last 60 days, it spent $2 or $3, and you’re not even targeting those keywords.
For example, you’re targeting 100 keywords and five of them are getting spend, and the other 95 are hibernating. You could take those 95 out and put them in their own campaigns, five in each campaign. Give them a big daily budget, starting with a low bid and working up. Instead of those keywords losing out to the top 5 that are taking all of the budget, they’re able to spend across all the different keywords by putting them in their own campaigns.
Having a large budget means that Amazon won’t throttle you. For example, if you have a $10 budget, a $1 CPC on average, and 30 keywords, you won’t even be able to afford to get one click for every single keyword, every day.
However, if you are willing to spend $100, $500, or $700 a day, where it will be 30 cents, 50 cents, and 70 cents per click, then Amazon will find the most effective way to bring you as many clicks as possible, bringing a higher chance of converting using that method as opposed to lowering the budget.
You can add a custom bid for keywords, where Amazon will show you the bid range and impression share. Spending more money will allow you to get a larger impression share. For example, if you notice that you’re already targeting some keywords and you have a very low impression share, it is worthwhile spending a little bit more money.
You can wait for a few days and if it is not profitable after a certain number of clicks, wait until it’s exceeded the target customer acquisition. For example, if your target customer acquisition is $8 and you spent more than $8 with no sales, start cutting them down.
Use the process of launching campaigns, discovering new targets, optimizing bids, launching new campaigns, and repeating.