Less than perfect decode

I'm not even sure if I can state my question clearly enough, but here goes.

By design, the WSPR protocol has FEC which allows for a decode even though some received bits are missing.

My question is: From a time perspective, what's the minimum window of reception in order to "completely" decode the data embedded in a WSPR transmission? Or is the better question, how many bits of data (stated as a percentage of the total number of bits encoded) are required for a successful decode? I'm not seeking precision in the answer, only a ballpark idea.

I have a similar question about JT-65 and JT-9 but that's for another forum.

It seems apparent to me that I am spotting and I am being spotted when only a relatively small portion of the two minute window is successfully received.

Thanks for any insights.