>Just because you spent time constructing an argument doesn't mean it's cogent.

I'm (perhaps mistakenly) equating time spent constructing an argument with argument length, since longer posts tend to take more time to write. It's also fairly well established that longer posts tend to be of higher quality on most message boards, and I'm equating cogent with quality (again, perhaps mistakenly).

time -> length -> quality, therefore invoking the law of transitivity time -> quality.