Offline LK HR farming

I really wanted to make a mosaic sin build but I'm offline so I thought the chances of farming 2mals and 2 guls would take forever. I started with hell countess thinking maybe I'll get some ist's or eventually cube up for the guls (just playing through a few characters I got lucky with mals). Then I do research and everything says to do LK runs on 7p mode.

My question is, is 7p LK really this profitable or did I just use up all of my luck for the rest of 2025? I can guarantee you I only did 8 hours of LK runs past few nights because I was listening to a podcast. I got 1 um (which I cubed to an ist), 1 ist, 1 Gul, 2 sur, 1 ber. Was able to make both mosaics pretty quick, was I just extremely lucky? Or is that how LK always is on a high player count?