Test your prototype with users for feedback. It saves time, effort and money by catching bugs errors usability issues, by letting users use/misuse the prototype, that you might not have anticipated.

https://www.youtube.com/watch?v=UVEQCNM6X-A&list=PLSbuwvHoXIcPuFJiXzIpHM3nt2QBWdaNx&index=6

Reasons to test your prototypes and features:

The Top 7 Usability Testing Methods | Adobe XD Ideas

You can decide which features to test and keep based on certain conditions:

Further Reading:

Test Stage | Stage 5 in Design Thinking Process | Yukti