Our work is organized around epics, which are the unit of business decision making and prioritization. Each represents a higher-level business feature or technical task. Epics are divided into user stories and take usually 1-3 weeks to finish in a team.
Our team works in a kanban-ish process where we pull stories from the epic, mixing in bugs and sustaining tasks as needed. There are no time-boxed sprints. We follow the rule that WIP is limited to 1 epic.
The problem I've noticed is that there seems to be a lot of time wasted on the boundary between epics. Towards the end of work on an epic, we get increasingly blocked by lack of tasks we can work on or dependencies. We've tried increasing WIP to 2 epics but it didn't help much - there's still hesitation and waste before we open a new epic.
How can we improve our process to eliminate wasted time on the boundary between subsequent epics? Does limiting number or epics in progress make sense? Should we put a limit on WIP for stories only?