You're likely only about 3x oversized for the peak load on design day, and only ~2x above where was tested for it's AFUE numbers (IIRC the standard size factor for AFUE is 1.7x design load.)
Let's make some worst-case scenario estimates.
Look at the curve (SDL-C111) for the furnace in figure 1:
If it's 83% efficient at the 1.7 oversized point (roughly the 0.6 point on the curve) that's about 95% of steady-state, which means the raw combustion efficiency is a near-condensing ~86-87% (which is credible- it may be controlled to be just below the condensing threshold). Have you had it's raw combustion efficiency tested?
If you're 3x oversized for the max load, move to about the 0.3 point , which is more like 90% of steady state, or 87% x 0.9= 78%, which is on design day.
Your AVERAGE load for the season is likely to be roughly half your design day load, which is the 0.15 point , or about 85% of steady state. 87% x 0.85=75%. (Which believe it or not, isn't terrible for a non-modulating single-stage system! Most real-world heating systems in the US are pulling less than 70% true efficiency.)
With the low mass of a hot air furnace, a 6 minute minimum burn isn't nearly as lossy the way it would be in a cast iron boiler. The abandoned BTUs in the heat exchanger are likely less than 10% of what it would be in a high mass system. Bumping the hysteresis a bit probably wouldn't hurt, but won't be miraculous.
Now, if it's an electronic ignition, induced draft- sealed combustion unit, see the comparisons on figure 6. You could be getting 85% out of an 83% AFUE furnace at your level of oversizing.
At 169K-in and ~86% raw thermal efficiency, it's steady state output is ~145K, so if 3x oversized means your design-day heat load is ~48K- which might be high for a small house in MD, but reasonable for a 3000'+ pre-1980s stick-built. If it's 4x oversized, it means your design-day peak is ~36K, which might be about right for a pre-1980 2500' house.
Even a perfectly sized furnace won't run more than 50% duty cycle throughout the day except on the coldest days of the year. The actual design heat load typically occurs for only a few hours at a time, usually between 2-6AM. But by the afternoon of the same day the outdoor temps will have have risen 15-20F from the low, and if there's a bit of sun the heat load for the afternoon will be less than half what it was when it was between 2-6AM when it was running constantly, yet keeping up. So 25% average duty cycle for the entire month of January means it isn't terrible. But unless it's a very large or very drafty house, I'd be surprised if your actual heat load is ever the full 145K.
Assuming you're actually running in the ~75% range (which is likely) a 2-stage 2x oversized condensing furnace will likely cut your fuel consumption by 20-25% (true as-used AFUE ~90-94%). A multi-stage with a continuously variable ECM motor blower like the ekoComfort would likely cut it by ~30% (true as-used AFUE over 95%).
Done a manual-J heat loss calc (or similar) on your place yet? Things could be better (or worse) than I've outlined.
Better than manual-J: Measure your fuel use and correlate it against heating degree days. Then with 25 year weather data for you zip code your 97th percentile binned-hourly heat load can be calculated to a high degree of accuracy.