I love this question. What's one thing you know about design other designers don't believe is as crucial as you? My answer this week to this would be this. One of the areas I've seen the most benefit from developing in my practice is the design handover process. I've seen happier teammates, fewer design-related bugs and better results.
Starting a design, plan the level of fidelity that the handover needs. If the tickets are a quick flyer, a sit down with the developer might be enough or a well-written description in a ticket.
If the design is more elaborate, you may need to have the works, prototypes, annotated mocks and flows defined and a big handover meeting.
I think we have lost something in recent years with tools like zeppelin or Figma on annotated mocks. Designers feel like they don't need to annotate designs anymore. We should try so developers have the correct information to focus on the build.
Designers should focus on the flow, the state changes and the detail of the experience. Nothing happens by chance. The devil is in the detail and how we convey this. We shouldn't expect the developers to have to make decisions about the experience. They have enough to do.
Suppose we have done all the right things if we've collaborated with the squad, the Developers, BAs, etc., throughout the process. Ironed out all the issues. The handover will feel like old news, which is good as you've already done all the work.