The physical time constants for the system for demonstrating refueling (the effective energy and particle confinement times) are far, far less that 10 minutes to get to what is effectively a steady state. Anything beyond a few tens of time constants is unnecessary when demonstrating steady state operation for a physics demonstration. Anything beyond that is engineering development and adds cost and complexity for no compelling reason. There is plenty of physics to study between where they are now and an effective steady state. They will probably run into operating limits due to space charge limitations and micro-instabilities driven by non-thermal energy distributions and large gradients in the system.
http://episteme.arstechnica.com/eve/for ... 3006482931