AT1 FY21 - General Discussion + FA, page-462

That rule applies to great companies, yes
But for AT1, first, the track record for the stock is not good at all, the stock performance hasn't given me enough confidence. Secondly, we know the product is great and all, but we still don't know how much they can sell and expand, we don't have enough information. Lastly, they are so many other opportunities out there, the opportunity cost is way too much.
I don't mind holding and have a paper loss now, I would not add to my position in AT1 unless it shows solid sales numbers. We are a manufacturing company after all, not a Bio.
All in my own opinion of course