Make up

If you are running set consists of trains I could see where this could be used, but if you are running mixed freights I don't see where its going to be very useful other than possibly a long -short combination.  A better bet is to make the fleet more reliable with consistent weighting, free rolling trucks, properly adjusted couplers, etc.  That way every consist will have a good tracking.

Another Thought

One thing to keep in mind is allowing trucks a reasonably full range of movement.  The "three point suspension" idea (tightening one screw to allow the truck to turn only, while the other is more free to rock), can get you into trouble with random train consists as will happen during op sessions.  I've found that derailments can be greatly decreased by allowing both trucks to both turn and rock in all directions.  Cars that are relatively light and/or long benefit from the ability to lean a bit on the trucks.  If one truck is so tight it can't rock sideways on the bolster, it's far more likely to cause a derailment in someplace like a helix where it has to handle a lot of curvature.  One screw can still be tighter than the other to keep the car from slopping around.

Work on the bolsters if needed to eliminate obstacles to trucks rocking.  Some cars, like Accurail's 89' pig flats, and the old Front Range ACF covered hoppers, have problematic bolsters that interfere with truck movement.  In some cases, the easiest solution in HO is to go with Kadee trucks with the "self centering" bolsters, which transfer all responsibility for truck motion onto the truck bolster assembly, and require only a flat mounting surface.  I've cured a few problem cars by filing the body bolster smooth and adding Kadee trucks.

Thinking model thoughts

I agree with Dave.  I've never cared for anything that forced my operators to think "model thoughts", i.e. thinking differently than their prototype counterparts.  If there are equipment or track issues, I think everyone will be happier if you resolve those rather than introduce guidelines that destroy the illusion we're trying to create for our guests.

I agree with the keep things

I agree with the keep things the same weight or very close. Then all the cars will behave in a similar fashion.

It's all about standards

The La Mesa Club has reliably run long trains of mixed equipment up and down a 2.25% ruling grade for several decades.  Success has been achieved by adherence to standards developed and adhered to in that period.

There are short and long videos describing the standards on YouTube.  Search for "LMMRRC Car Dep't." or "La Mesa standards".

Don M.

Prototype thoughts

Prototype trains do have certain placement restrictions (can't have a continuous block of 20 loads behind a continuous block of 20 empties, can't couple a car over 89 ft long to a car less than 39 ft long, if you have DP's or mid train units the tonnage has to be distributed properly, can't have a long empty car in first 10 cars, etc.) but they still have loads and empties, heavy and light cars mixed.  The placement restrictions don't neccesarily scale well.  Train placement restrictions in a train that is 110 cars long is a different scope than train placement restrictions in train that is 10-20 cars long.  Plus in the model world, actual equipment weight has nothing to do with "waybill" weight.

" in the model world, actual

Yeah, all house cars or covered hoppers can be weighted the same ,only hoppers,gons, and other open cars can take advantage of the loads to make loaded cars heavier than empties. If we want to try to create the visual illusion of reality we often have to use different methods than the prototype or the modeler who wants to create a small scale based system of train makeup( real trains and model trains have different characteristics and goals,so need different systems to maximize their operating reliability) .......DaveB.

Prototype restrictions

Understood, but to me, there's a world of difference between desiring to replicate those restrictions and blocking your train in descending order by car weight.

Remember that car weight is based on length.

A 40 foot car, a 50 foot car, and a 60 foot car weighted to NMRA standards should function similarly and be pretty much interchangeable.  I'm not sure if wieghts scale up to an 89 foot car next to a 40 foot car.

Live loads and clarifying comments

Three Point Suspension

I agree with Rob on the "three point suspension" problem.  I tuned all of my otherwise properly weighted cars in this manner because I had read so much about it.  The result was a lot of random derailments, even on straight track.  Loosening the tightened truck resolved the issue.