Eh it's nothing special, it's just a really rough estimate of how much I've done in my playthrough, I check SkyComplete on what Vanilla quests I've done and just estimate on that number of how much I have still to do.
Thing is I have so many DLC size and quest mods I can't really give an exact number because most of these are completely new for me and I have no clue what to expect.
For instance I didn't touch Wyrmstooth (which I could speedrun though, I played this mod so often by now), Falskaar, Undeath (Never made it past the second quest), Beyond Reach and Summerset Isle (totally new), Wheels of Lull (so hard I ragequitted it last playthrough) and I still have to play all Legacy quests, I've only found Ulgarg's body for Shattered Legacy in my last playthrough and that's it, never progressed further. I still have to visit the Reach in my current playthrough as well so that can still take a while.
It could very well be that I still have a thousand hours to go to finally complete my playthrough
Ahh, okay. Yeah, the quest mods add so many hours to the game that it is difficult to know exactly how long you will be spending playing the game or how far you have come to total completion. I think I will skip that part then, in my playthrough.