How long should a tsuka be?

Could you please elaborate on the ideal length of a tsuka, the handle of a traditional Japanese sword? Is there a standard measurement that swordsmiths adhere to, or does it depend on the user's preferences and the sword's intended purpose? Additionally, how does the length of the tsuka impact the sword's balance, handling, and overall performance? Understanding the significance of this aspect is crucial for those seeking to appreciate and potentially wield these ancient weapons.