Let me try describing it one more time.

1-set your end bell to 45.
2-use graph paper where each vertical is .5 amps and each horizontal is 1000 rpm
3-Run the motor in the test that tells you rpm and current
4-plot 10 points at 10 rpms (current and rpm)
5-start a new curve and repeat all steps at 50 degrees or 46 degrees (your choice)
6-repeat step 5 with different timing marks
7-interpret the data (40 degrees)
1-for example the slope up to peak below 40 degrees (on your graph paper) will be an additional 1 amp per 1000 rpm. (For example)
2-peak efficiency (0 slope) will be .5 amps per 1000 (but this peak is at 9500 rpm)
3-slope down or negative slope will be 1.5 amps per 1000
8-interpret the data (45 degrees)
1-same as 7.1
2-peak efficiency is at 10000 rpm
3-same as 7.3
9-interpret the data (46 degrees)
1-it takes more current per 1000 rpm than 7.1
2-peak efficiency is at 11000 rpm
3-same as 7.3

What did you learn?
1-46 degrees takes away low rpm efficiency (comparing 1 curve to the next)
2-45 degrees retains all low end torque but you peak at 10000 rpm (this is a great curve for short tracks with lots of accel and deceleration)
3-the slope down from peak is almost always the same but adding timing moves the efficiency peak to higher rpm
4-you dont ever want to cross over the negative slope side of any of your curves so the max rpm you need on a track should never exceed sit outside this rpm
5-some of the negative slopes are sharp and some are shallow.
6-calculate the average rpm you need based on fdr and roll out. If you negative slope was shallow set the timing and fdr so that you rpm needed is at the average rpm you want. If the slope is sharp set the fdr to a little less but leaving timing alone so that your max rpm stays inside the curve you drew.
7-all of these curves can be compared to other motors and they will be accurate even if you dont know the exact power or torque

you dont have to plot 3 points. It could be 10 points and they can be in 1 degree increments or whatever you like but the slope down from the peak will be consistent. The slope down (negative) will look like more current in and less rpm out.

For example the points you plotted before the 0 slope. 45 degrees=2 amps per 1000 rpm, 1 amp per 1000, 3 amps per 1000.

Ill try to do a video but maybe my clarification helps.