Incorrect Guppy, starters are varied, so are electrcal systems, so are engines..start up a Garret Dash 10 and let me know what your start speed is vs a Pratt PT6, vs a JT15D, then tell me all starters max at 18-20% N1/2/3
The Garrett TPE-331-10 is best run to max motoring RPM prior to the introduction of fuel. Garrett (Honeywell) strongly recommends it.
You've probably not had the opportunity to use the rapid start system which is an option on many TPE-331 installations. This system increases the starter voltage, spinning up the engine in half the time and to a higher speed. The reduction in start temperatures is dramatic.
Without the fast start function or with it, Honeywell still recommends that the TPE-331 be motored to max max motoring speed on the starter before introducing the fuel. The faster you spin it, the better.
What the actual start speed each powerplant achieves is really irrelevant; take it to whatever the start motor will deliver. If it's on external power or has a very good battery, it may be higher than a normal battery start. Regardless, your start will be cooler and the engine life increased, the higher the motoring speed before introducing fuel.
You may not have bothered to read past your checklist or look into the manufacturer recommendations. You should try it.
If you flew a variety of Jets and turboprops, with and without GPUS/APUs...24 volts vs 28 volts, you would know the difference..
What are you attempting to say?