I have never noticed a lack of time....I just click on the Modify header and type in my revision. Am I not understanding the problem?
After you've posted, if you decide to change something, it puts a stamp at the bottom of your post saying you edited it. If you could catch it before the time limit (which was only 3 seconds I believe) the stamp wouldn't show up. Capt increased that time to 90 seconds now.
So if you can catch your mistake and fix it before 90 seconds, no one will ever know now.
The message should look like below.