Thanks, Mark, for posting this. On a recent crawl with a client who wore the paper suit I issued him, we found more than several SPF (I know, I know) floor joists with extended longitudinal splits. (Sorry no pix) Most showed no deflection to the eye. I suggested sistering, but had no real references. Because I could see no deflection I opined that the splits were from desiccation, not stress from load, and I suggested even 3/4 plywood screwed on. I don't remember if it was this forum or another, but an architect on one posted that no fastening procedure that depended on glue, or any other kind of "goop", had any science or reason to support it.