hey phonebooth
topical spironolactone is fairly rapidly metabolzed at the scalp and rendered ineffective, so twice daily application will ensure an on-average higher amount of available spironolactone than a single daily application and should mean that more non-metabolized spironolactone is available at the target area.
So yes, if you don't find it too much of a hassle, a twice daily application (with 12 hours in between) is probably a good a idea.
You might also want to look into 17a-estradiol...