You only see that one 2 (maybe 3) times then it's gone for good. A shame really, it would be nice to see it more often, maybe every 10th pane so as not to be too generous but still be often enough to keep people logging in every day.

You see it two times.
First, it's 1 FG every day for 10 days. The second is 1 FG one day, 2FG the second day, for 10 days. And that's all. After that, it's just the classical panel with 2FG at day 5 and 10.

And event if there is a 6* for 350 days login, it's not related to the panel. The 6* comes with the every 50 days (I think it's that?) reward and not as a reward of the panel. So, we need more 10 FG panels.