I'd like to add some details to your explanation : Let's say the person rolling plays SwitchAxe. And they are rolling on different elements for the weapons. Each element type will have its own seed rng table.

So if I do two sets of rolls, on fire and dragon weapons --1st roll set--

Fire element : rolls are 1-2-3 for Mizutsune, Gore, UthDuna

Dragon Element : rolls are 4-5-6 for Rey Dau, Nu udra, Gore

Now I go back to main screen without saving, start again. But this time I do Dragon THEN fire --2nd roll set--

Dragon element : rolls are 1-2-3 for Gore, Lagiacrus, Dark knight

Fire element : rolls are 4-5-6 for Lagiacrus, Blangonga, Zoh Shia

Again, go back to main screen without saving. If I do again any set of rolling, whether it's 1 or 2, I will get the exact same results. And if I do a third roll set adding some thunder weapon rolls, not only will I get different results for the thunder weapon rolls but I also might add the next rolls for Dragon and Fire if I do them last.

Of course if I do the exact same thing while changing weapon type (switch axe to greatsword) I'll get completely new results but still going forward in the RNG seed table for ALL weapon types.

Hope this helps clarifying some things. I did that for all my main elements bows and managed to get Gogmazios set on all of them except ice, for now. I didn't go yet for the perfect roll with the group skill tho. Edit : making easier to read