Comments by "SmallSpoonBrigade" (@SmallSpoonBrigade) on "Why Cities With Grids Are Terribly Designed" video.

Indeed, the grid leaves traffic designers with a lot more options when it comes to routing traffic. With a cul-de-sac system, if a key road needs to be closed or has heavy traffic, there's no guarantee that drivers will know how to route around it, and there may not be a good way of doing so. A typical grid city will have a system of main arterials and side streets. People wouldn't normally be driving down side streets until they get close to their destination, hence why they tend to be narrower. The ones around here are basically one lane roads in most parts of the city with a parking lane on either side. It tends to keep speeds lower as you do need to pull off to the side of the road if a driver is coming from the other direction. Contrast that with the suburbs, and it's a right proper mess. You're not going to know how to get anywhere without a map and/or gps and if you do miss a turn, you may not even realize it for quite some distance. The solution here is really to fix the zoning so that there's more mixed use where it makes sense, improve public transit (BTW, mass transit, apart from subway, is a whole lot easier to do if you've got a grid layout to a city) and ensure that the streets you mean to carry the bulk of the traffic are set up to handle it.
2
A grid city can pretty much avoid all of those issues if it's set up to do so. The issue more than anything else is that a grid system allows you to avoid mixed use zoning in a way that the alternatives don't. IMHO, a grid city with mixed use will always beat cul-de-sacs and other less orderly arrangements of streets. You can always close off individual streets if you need to and so long as you don't allow people to build on that extra space, you can always reclaim it if need be. But, trying to create a grid layout if you don't already have something along those lines is incredibly hard as you're likely to have to bulldoze a bunch of buildings.
1