They should at least give you the option... if you tell it to "Avoid All Delays" - it takes you clear to hell and back, like 3 hours out of the way in my area.
I find "minmizing delays with fastest route" does a good job... but again, it's a manual selection.
I haven't had any major problems with re-routing. The one time my unit did automatically re-route it used the second fastest (and closest to my main route) route.
In my case, the secondary route ran parallel to the primary route along an almost identical path, just about two miles apart; the main difference between the two different routes is the primary is a four lane Interstate and the secondary route is a three (sometimes two) lane highway that turns into a regular city street about 1/4 of the way before I reach my destination which adds about 10-15 minutes to the drive because of the lower speed limit and stop lights. If the delay reported by TomTom Traffic had been closer to 10 minutes rather than 18, I'm assuming it would not have bothered to re-route me.
I'm guessing in you're case, there are no alternative routes that have close to the same amount of lanes or speed, therefore your TomTom does not re-route because it assumes driving on a road with fewer lanes or a lower speed limit will delay you even more.
If that's not the case, you can either hope this gets corrected in a future map update or make a map correction by marking the general spot where you should be re-routed starts and make an "other" comment explaining there is an alternative route that can be faster; giving street names if possible. Using the "other" option on map corrections is tedious, but should help in getting your routing problem resolved faster.
Logic tells me because you're not in New York City or Los Angeles, that map corrections aren't reported or utilized as frequently; however, Portland's metro area is only about 1/2 million people smaller than Minneapolis/St. Paul's, and I'm getting good traffic routing (so far), so I assume map changes reported by your local municipalities would be at about the same rate as mine.
Having said that, my actual hometown south of Minneapolis has had a round-a-bout in use for at least two years. Even after reporting it as a map share correction on map 7.10, map 8.25 still doesn't show it.
Tele-Atlas, as well as any other map maker, is dependent on correction reporting by the municipalities themselves. If the municipality builds, widens, or changes the speed limit on a road and doesn't report it to the map maker, the only way it will change is through a user reported map correction. God only knows how long it takes a rarely reported map correction not made by a municipality to make it on an official map release
