True, do it all the time on the old 6v tractors. Starter will spin faster. Just don't grind on it for extended period of time.
The engine should start up faster anyway. On the old 2 cyl. Deeres, I just pull the start knob and quickly let off, engine is running.

57 GMC LCF 370
55 John Deere 40-W
59 John Deere 430-W
2000 GMC 4x4
56 John Deere 420-W
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