Hey man,
In my experience U .Larges are pretty funny. Roughly 1 every 1,000 planets but that is U.CLASS.
For me as well bthey tend to cluster.
So I`ll get an Eden, then a Rich and maybe a Fert
BW knows the code so theoretically it should be randomn.
But I know from experience that Larges and Ferts are the hardest to find.
There is of course the Viral phenomenon, but whether that`s true or luck I`m not sure but I have experienced it, where you get more than normal VClass.
I`m Miner on RT, and if I want to explore I know minimum i`ll need to plough through 500
ALSO
2 really important things to remember
1. How many other people are exploring e.g. when you see the numbers 0001,0002 etc. you see the gaps as to how many others are exploring at the same time. So you could just be unlucky, as this decreases.
In downtimes I like to explore as I know I will move through the sequence
2. For me I know what BW says, but I do tend to find better planets at dig times. both AM and PM, also during UW`s
Why that is I`m not sure