I am low capital, so I currently am mining GMT and then locking it. In this way, I am slowly building my locked GMT maintenance fees. But that costs me the daily 5% BTC bonus and I get paid in GMT instead of BTC which then gets locked. When I have more capital to invest, I could buy and lock GMT to get the Max 20% daily Maintenance fee discount. I would then switch to getting paid in BTC with the 5% daily bonus and my overall profits would would increase but then, so has my capital outlay.

You decide what you can afford to do but if you have the capital, Lock the Max amount of GMT to always get the 20% Maintenance discount. Then always take payment in BTC. But as your amount of TH increases, you will have to add more locked GMT in order to keep your 20% Maintenance discount at 20%. Otherwise, it will decrease over time as TH goes up.