depends on your kit. A 2gf kit ya use 2g (2000mg which is one cart) and gives 75mg/ml at 23-25ml total yield. The 4gf does 4g of fina, 75mg/ml 50ml yield a,d the 8gf converts 8g of fina, 75mg/ml 100ml yield.
Most people say not to go over 6 weeks with fina.
The longest I went was 12 weeks, but I adjusted the dosage to every 4 days.
The first 6 weeks OED then the rest every 4 days.
I was just experimenting.