Update this topic - time will fix it. So difference in DVB-T and DVB-S is that in Terrestial side EPG data comes more or less immediately when channel is tuned but in Satellite broadcasts it seems to take a while. And that while in my case might be pretty long but within few days data always gets updated in decent way.
So at least in my case with Thor satellite and Nordic satellite operator it seems that EPG gets updated in fairly tiny pieces day by day and eventually within a week it gets as it should be. This was clearly visible when one channel I typically follow changed location and I retuned it. In first few days EPG was very unrealiable but within a week it started to look normal.
Terrestial antenna broadcasted EPG gets fullfilled more or less immediately. It is probably related on way EPG data is uploaded in broadcast.
So nothing really done but problem fixed by time
Still one thing what I am not sure. If I do not tune to certain channel from DVB-S for a while will it update EPG despite that. I have feeling that not watching some channels for a while might cause some lack of EPG data in satellite broadcast. However I am not sure about this or is it just a wrong impression. The significant EPG lacks are pretty rare in my systems nowdays.