You don't want the car too tight on bolsters when you have hard transitions to grades or any relevant fast height change. (I've had to loosen some. They need few degrees of play there, still room to tighten many though; your right. It improves geometry on flat track, keeping the trucks planted)
The tight S turn issues rear their fangs more with body mounted couplers , long cars and or small flanges of 2r than our "toy" flanges. The factors still exist in O, just not as strongly. The subject in HO circles seems as constant as "clean your wheels".
You won't make the S with a Marx A-B/ A-B-B engine nor a few other items. Some couplers are guided by compound leverage off the truck; sort of a lead to keep the coupler shafts at an optimum angle for the track. (coupler aligns itself for coupling in a curve.)
You MUST have a 1/3- 1/2 straight between opposed curves to allow the trailing truck to get off its curve. Because #one car's rear truck is on a curved left, coupler goes left when still over the last piece of track occupied. But the #2 car lead truck is still on the right curve, so it's coupler is turned right... the opposite way. (Marx cars aren't that way, just the B units. But I have seen cars decades ago that did it too)
The little straight also helps other trucks/couplers transition the S better.