When deciding whether animations should play only once or repeat as users scroll, you need to consider the impact on user experience. Setting data-aos-once="true" on an element ensures that its animation only occurs the first time it enters the viewport. This is useful for content that should not distract users with repeated motion, such as introductory banners, headers, or call-to-action sections. Using one-time animations can help maintain a clean and professional feel, especially for static content that users may revisit as they scroll.

In contrast, allowing animations to repeat (data-aos-once="false", which is the default) can be appropriate for interactive sections or elements that are meant to grab attention each time they appear. However, overusing repeated animations may become distracting or overwhelming, so it is best to reserve them for key interactive components.

As a best practice, use one-time animations for elements that introduce important content or for sections that should feel stable after their initial reveal. Repeating animations are better suited to elements that benefit from ongoing attention. Always test your choices to ensure the overall flow of your page feels smooth and engaging, not disruptive.