It is commonly considered that the Bushman brand of Personal Mosquito repellent is the best one available. This contains 80% DEET, and quotes protection time of up to 15 hours.
Comprehensive tests http://www.bushman-repellent.com/pdf/bushman80.pdf PDF source document seem to show that no bites were recorded, in the first 8 hours of use, using DEET Bushmans Plus, and none in the first 11 hours with the Bushman Heavy Duty lotion.
The Locations keep working for a longer period than the Aerosols, as shown by these manufacturers quoted examples.
I would estimate that the Aerosol, shown above with a 7 hour rating, would be good for 4 hours full protection against bites.