Lore 5 creator, with +3 frequency, two invokes for a strength 9 potion. That gives you 3 aspects on yourself per drink, and you can drink 4 times for a total of 12 aspects (each can be tagged once for free). That looks pretty good to me. Nothing wrong with "ridiculously lucky" as an aspect. Indeed, given how it works in Harry Potter, I think you could even be compelled into a situation that looks bad initially, but is good in the long run (which gives you a fate point to use on your aspect to help keep things going).
Of course, the above requires a pretty skillful person to make. That said, anyone can do this, with sufficient lore and the right aspects when creating the item. With just Lore 4, you can put the frequency up to 5 uses, then invoke 3 aspects for a strength 6 effect (for 2 aspects placed per drink).
Hmm, looking over the potion rules, I am starting to think there's no technical upper limit to potion strength. I'm going to track down the thread where people were talking about that.