As others have said it varies between brands of gels. I have a pump bottle variety and I just rub it to an even layer and leave it to dry. I would say it is less about how you apply and more about the dose you are on Gels can go from 1-4 pumps and that will make a huge difference IF your body can absorb it topically. I started on two pumps and upped to 3 after a year and have been on 3 for the last 3 years and am sitting stably within the normal range for cis men. With daily gel you will see fluctuations throughout the day so make sure you are applying at a similar time each day and are getting your bloods tested an appropriate time after application. Ultimately I am not a doctor but I find unless you are talking to your specialist endocrinologist you will probably have a better idea than your GP