Hmm... everyone is different and I'm not sure I'm the best representative of the "flow state" crowd. For one, I'm a DS not an SWE. Also I tend to do more research-y projects, projects where the requirements are vague at the start of the process and a big part of my job is requirements gathering. Projects that aren't super time sensitive TBH. Jira rarely works well. So the projects that have worked best for me involve lots of brainstorming meetings at the start, then documentation (literally Word docs), then development work, then restart the cycle. The worst projects involve stakeholders who want to make science decisions in real time. If that makes sense? None of this may apply in your world.