Our work (architecture) falls generally into predefined stages/phases in a TPM format since our design contracts follow sequential development. Within stages is another matter, as we increasingly find our clients' needs to be less sequential (agency approvals, sub-packages, fast-tracking) and ourselves resolving items as they arise - much more suited to Agile/Kanban workflows. We love the Kanban capability of the task lists (our teams employ a 5-step hybrid Kanban: backlog -> week ahead -> in progress -> completed -> review), but using them in this manner renders the timeline mostly useless. What would be incredibly useful for our teams is a way to group multiple task lists (in the Kanban format) under a phase or stage on the timeline. The stages can remain high-level sequential "waterfall" milestones (with their own dependencies) for our team and clients, but our day-to-day can operate in more collaborative sprints/charettes on the task list.
A alternative way to achieve the same would be to offer progress/status for each task and a filter in the task list view to reorganize by status - MS Planner offers a similar functionality in 365. Perhaps building on the mark urgent option, a status button? We could then organize each task list as a stage/phase itself, but our day to day view could be organized by status.
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