SAFe has a Continuous Delivery Pipeline (CDP) wherein work flows through it starting from big idea/concept (or just work within the context of the team/program … i.e. extra features to a product, technical debt, innovation work, etc.)… to it becoming something of value/cash. The elements of CDP are: 1) Continuous Exploration (CE)… this where features making up the product (MVP)/idea/program work are created and developed, 2) Continuous Integration (CI) … this is where the stories — prioritized and decomposed features are turned into stories — are created, designed, built, and tested in two weeks iterations; 3) Continuous Deployment (CD) … stories are deployed to production … and then 4) stories / feature set get released on demand.
Now… if features are not developed in CE… and sent to be worked on by the agile teams in CI… then it becomes a bottleneck … and source of frustration… 
you are setting up your team for failure…there are only 2 weeks in an iteration/sprint… hardly enough time to discover all that needs to be discovered for a feature …not to mention the stories that comprise it! Worst, if you need other teams to help… you have a handoff item for them to work on… there is a chance that they cannot help because their capacity is spoken for already and probably inflight working on whatever they planned for earlier in their own PI planning within their own workspace. So, plan ahead and work on and develop your features in CE!
The SAFe construct is this: Product Managers with his/her collaborators (Product Owner, Business Owner, SMEs, Architect, dev team, Business Analyst, etc.) develop features during the CE, not during the CI… regardless where the work enters from (Portfolio level or Program level … does not matter … a feature is a feature!).
There you have it… plan ahead as a team with lots of collaborators … feature development is like a mini JAD session … with a lot of impacted and helpful people … don’t do it alone …share the wealth … share the fun! Deliver value together! Share your success!
