If you are seeing the error message,
"Your Amazon API requests have been temporarily throttled. Please evaluate all applications using the Amazon API, including Wordpress Plugins and other applications"
This means one of your products tried to update but it was denied by amazon since you hit your limit. This won't really affect the customer on the front end. The product will attempt to update again a few seconds or minutes later based your settings.
If you are new to amazon and building a lot of stores or even if you are building one store but adding thousands of products which we don't recommend then you might have API throttling issues.
If you have 5 or 10 stores, they all share the same limits because you will be using the same amazon keys for all your stores and they all share the same limit.
The information below comes directly from amazon regarding your amazon API request limits and how it works.
If your application is trying to submit requests that exceed the maximum request for your account, you may receive error messages from Product Advertising API. The request limit for each account is calculated based on revenue performance.
Each account used to access the Product Advertising API is allowed an initial usage limit of 1 request per second*.
Each account will receive an additional 1 request per second (up to a maximum of 10) for every $4,600 of shipped item revenue driven in a trailing 30-day period (about $0.11 per minute).
You can verify that your sales are being attributed to your calls to the Product Advertising API by checking for the following:
• You are using the links provided by the API when linking back to Amazon.
• Your Associate account and Product Advertising API account were created using the same Amazon account (i.e. email address).
• You are passing your Associate tag in all your requests to the API.
* New applicants are limited to 8,640 requests per day, once this limit is reached your account will be limited to one request every ten seconds. Once your application is fully accepted into the Associates Program this restriction will be removed. "