What issue does sequential testing commonly face?

Sequential testing, which refers to the method of evaluating multiple variations of a subject or concept in stages rather than all at once, often encounters significant challenges when it comes to testing items in isolation. This method can lead to the failure to capture the interactions among variations, as each test is performed in a vacuum without considering how the results of one test might influence or correlate with others.

When items are tested in isolation, the insights gained can be misleading. This limitation makes it difficult to understand the holistic performance of a campaign or product, as the interactions between different elements can greatly affect the outcome. A comprehensive understanding of how various factors work together is crucial for drawing accurate conclusions from data and making informed decisions.

While issues like combining tests effectively, running tests too frequently, and overlapping test timelines can pose challenges in testing practices, they do not inherently address the fundamental issue of losing contextual relevance in data when items are not considered as part of an integrated system. Thus, testing in isolation is a critical concept to grasp in the context of sequential testing issues.