As a little history, after the '88 Olympics the Olympic Committee was hoping to eliminate sailing. It was too expensive to put on and was not viewer friendly.
So, they asked us (RC at the Miami Olympics Regatta) to experiment with new courses. The goal was to make courses that were more interesting and exciting and that would make for good spectatorship. This was done on all the courses.
I was PRO on the Tornado course, which later encompassed the 49er as well.
We experimented with gates at the weather end, leeward end and middle of the course. It was all pretty exciting to watch by comparison to standard courses -- the weather mark was actually dangerous, but the mid gate (starting area) at least stopped the Tornadoes from banging corners both upwind and downwind.
But, eventually the mid-gate idea was dropped. Again as possible dangers.
The leeward gate was kept and is still strong and thriving. We thought ten boat lengths apart were ideal at the time. We experimented with favoring one end or another. Particularly if the left side of the course was favored, we would try favoring the right mark.
Nice part about gates is it offers a place for boats to overtake other boats. With standard port-rounded gates, technically no boat should ever pass another boat.., as long as none of the boats make a mistake. With the gate there is that opportunity.

While many of the modern, hot boats prefer Windward/Leeward courses with gates, there are still a ton of classes that prefer a triangle as well.., i.e., the Hobie 16, Wave, Laser, Sunfish, et al.

For the Tradewinds we run the faster classes on an outside course with a triangle, followed by two W/Ls. That makes for a long course for them, gets them away from classes starting after them the first time around, and offers a bit of challenge on the triangle -- we set the reaching mark at a marginal angle where the brave can fly spinnakers, some not so brave may opt for JAM. The next reaching leg is deep and definitely a spinnaker leg.

This course configuration has worked well over the last ten years or so where you have a lot of boats and a lot of different classes and speeds.

Good luck with your renewed sailing,
Rick