IPMS is already "Win, Place, and Show",,,,that is the horse racing term for 1st, 2nd and 3rd, the judging system that IPMS uses.
Gold, Silver and Bronze is the other set, I believe started by AMPS.
In 1-2-3 judging, each model competes against every other model in that category. This doesn't mean that all Aircraft compete against each other,,,,,a category is "single place prop aircraft 1/72 and smaller" or "multi engine aircraft 1/48", etc ("Aircraft" is one division, not a category)
In Gold, Silver, Bronze,,,,,the model is judged with a score sheet against a point system, not against he other models.
so, if you judge 1-2-3, there is only one 1st place winner that day, and even a poorly built model can take first, if it is one of the top three there on that day in the category, on the flip side, you might have 6 truly excellent models that day, but, only three can wind up 1-2-3,,,,,if you judge G-S-B, there can be 5 winners of Gold,,,,,or Zero winners of Gold that day, depending on the quality of the finished models, so you you have 5 G, 0 S, and 2 B,,,,,,,,or 0 G, 0 S, and 4 Bronze. G-S-B takes a lot longer to judge at a big show, and you have to guess how many awards to order in advance.
I used to have a link to one contest's Model Score Sheet, but I forgot what they labeled it as, so I can't find it in my favorites. But, if you printed one out, you could pin it up by your workbench,,,,,and you could check your model the same way it would be checked at the contest,,,,,and you would know how well you built it, whether you took it to any contest or not. The sheet serves as a sort of summary of all the magazine articles and web pages you have read over the years, concerning quality of building.
I found the link, I remembered the club's name chattanoogaipms.squarespace.com/.../Chattanooga%20Scale%20Modelers%20Judging%20System%209-28-10.pdf
That PDF is useful four ways,,,,,,,you can pre-judge your model before you enter a G-S-B contest, you can use it as a quick checklist before you enter a 1-2-3 contest (minus the GSB differences) or you can use it for models that will never leave the house,,,,either to evaluate an already finished model, or to follow along and prompt you as you build at the workbench.
I hope this helps,,,,but, do take a look at the GSB scoring pages,,,,even non-competition fans can use that to improve their work.