How often you reapply depends on your conditions and care. Really hot temperatures and sun are likely to degrade the sealant as are lots of rain, acid rain, winter salt, etc. Also how often you wash, what shampoo you use, and your washing/drying technique will have some effect as well.
I would not consider reapplying once a month "wasting", but merely providing the best protection. After all, many use a spray wax at every wash, which could be more often than once a week, and no one accuses them of wasting spray wax. However, you may be able to get more than a month before the properties degrade to the point at which you'd like a refresh.
Setec's reasoning sounds logical. I figure it's better to stay on top of a vehicle's condition, rather than lag and wait too long between re-applications. This would help insure many years from the paint finish with little to no degradation as time passes.
On average, I'd say 5-6 weeks would probably be about optimum.
This all depends upon the time you are willing to invest. There are times, because of weather, or other personal demands, that one cannot refresh as often as they like. That's the purpose I suppose of using durable sealants, waxes or coatings. Less maintainence for the owner.
As also mentioned, many use spray waxes or other products like detail sprays after a wash, and something like Duragloss Aquawax, or another such durable but very easy to use product after a wash will help stretch the longevity of the initial-original LSP.
I'd figure on average, one will probably use about 1oz of WGDGPS 3.0 per application on an average vehicle, so this will give you some idea how long any given size bottle will last.
The product spreads well, and goes pretty far, and as others would say, just like I've found, laying down heavy coats adds no benefit and in fact can maybe make removal a little more work. 3.0 is an outstanding product, superb I'd say, and is very easy to apply and remove. Gives breathtaking final results!
Mark
