Again, there are many different opinions to quickly answer the question: every 72h is a good guideline for most PPC campaigns.
When it comes to selling successfully on Amazon, a well-planned and executed advertising campaign is critical. An important component of this is regularly reviewing and adjusting the campaign to ensure it is as effective as possible.
General
First of all, it is important to emphasize that there is no "general rule" solution regarding the frequency of reviewing and adjusting PPC campaigns. It depends on various factors such as the type of advertising campaign, the budget, and the goal of the campaign.
In most cases, I recommend reviewing the campaign at least every 3-4 days to make sure it's on track, the ACOS is low, and that keywords aren't being played out that aren't producing the desired results.
It is also important to keep in mind that seasonal and time-of-day factors can affect campaign performance. It may prove useful to check campaigns more frequently during the high season (around October - March*) or at certain times of the day to ensure it is delivering the highest ROI.
* The high season varies depending on the product.
Targets
In addition to regularly reviewing the performance of the campaign, one should also regularly review and adjust the goals of the campaign. This may mean that you have achieved certain goals and it is time to set new ones, or that the original goals are not being met and it is necessary to adjust the campaign to achieve those goals.
Summary
In summary, the frequency of reviewing and adjusting Amazon advertising campaigns depends on several factors and can vary from week to day. However, it is important to review the campaign regularly to ensure it stays on track and delivers the desired results. One should consider both the metrics (ACOS, CTR, etc.) of the campaign, the goals of the campaign, the target audience, and the spending in the estimation, for the best possible performance and clear estimation of the campaigns.