The problem with grade level crossings, even if the lights are adjusted, is always rush hour traffic.
One good example of this is line 512, St Clair W of the TTC. It's a street car on well separated tracks but with many intersections due to it crossing dense neighbourhoods in addition to dedicated left/U turn lanes for 2x1 lanes worth of cars. Despite being only 2x1 lanes, the road being on the E-W makes it a major thoroughfare. The congestion can get so bad that at certain intersections the street car can get stuck for ten minutes or more until the blockage clears.