In the race stint setup, the max number of stints available is 5.
http://igpmanager.com/play/?url=race-next#tab3
If one wants to do more stints, either one has to manually set "unscheduled stop" to get right amount of fuel and tyre type - or automatically stops choose the last stint settings for fuel and tyre type.
With 100% races, often the best strategy has shown to be six stints and with the new Super DRS we have seen seven stints being successful.
Now, I suggest that the strategy settings allow for up to seven stints (instead of just 5).
An alternative would be to have a maximum number of (dry) tyres for a race, but that would limit some strategy flexibility.