Hi Col - You are on the right track from the get-go. Some of this is for others following. Timing is always set to produce peak cylinder pressure at your engine's geometrical sweet spot (crank angle) for producing maximum efficiency and performance (including max power, torque, HP, economy*, etc) under any and all conditions (throttle, VE, temperature, manifold and barometric pressures, fuel type and grade, etc). This is why timing is variable, as conditions are always changing, but the target is always the same.
The timing values you posted will be different for every project, and are only generalized theoretical targets. As to tuning and dyno's, no two engines are identical, and no two fuels or conditions are either. If it was all the same, we wouldn't need dyno's or tuning. I see you get that, and are on your way to tuning for performance. I know which article you read, and John was right on the money. Follow its concepts. After that, we also need to consider how we use fuel and timing together in order to accomplish certain goals.
In the basic search for efficiency and performance, we can use our logs as data indicators, sort-of like a dyno. For example, we have efficiency indicators such as MAP. Under identical conditions, if the MAP indicates lower (more vacuum), then the efficiency is higher. You can figure-out why that would be true, and use that info to search for best performance, also incorporating other data indicators.
Likewise, an example of traditional efficiency measurement for drag racers is trap speed. This simply means the maximum speed attained on the run, where a tuning improvement results in a higher trap speed, and is typically used to find and set maximum effective timing at full-throttle, above peak torque. We can do the same thing with our logs, simply noting the time and speed in repetitive short runs at less than max speed, and in specific ranges that you can't do on the track. Tuning tricks. Find these timing end-points, then begin playing connect-the-dots as trends and understanding develop.
Finally, there are concepts in order to achieve goals, such as idle stability, cruise economy or throttle response. The timing you use at idle may be different, depending on what scheme you intend to use. For example, here is a random ignition timing table (Spark Table) manually set to lower-than optimal idle timing (timing 'valley' or 'trough'), in order to allow idle recovery. Here we can see that it creates a de-tuned "torque reserve", where timing (and torque) is increased if rpm falls lower than target idle speed, working to push the rpm back up automatically:
This is for concept, as Speeduino also has an automated feature for this that may be employed once the concept is clear. As you can see, you must first tune to find the max idle efficiency timing before you can begin modifying to meet your goals.
Other considerations may be incorporated into your timing, such as coping with det-limited fuel, or smooth starting from cranking transition. These are considerations beyond the basic target of peak efficiency, and different for every engine setup. While much of this can be sensed for felt for tuning improvements, analyzing info from your logs can be a big help in determining best direction to tune, and for finding issues or opportunities you didn't sense or know existed:
There are of course many more considerations throughout the range of operation, but I hope this adds to the conceptual direction you have already set yourself. The basic timing curve is only the beginning step in ignition tuning. Have fun!
* Note that economy is based on maximum efficiency of course, but some additional coordinated fuel and timing techniques are used to also introduce other energy-conserving schemes, e.g., pumping losses and effective compression. Beware—tuning may be addictive.