This is mostly good experience and sound advice. But nickel-silver can become brittle if it is overheated in annealing. This used to be a danger with the cupro-nickel jackets (substantially the same stuff, though sometimes with more nickel and a whiter hue) which were once used on rifle bullets. Bullets could break up too easily on a large animal, leaving him with some score-settling time, and bullets were known to weep tiny amounts of friction-melted lead core, making them assymmetrical in weight, and inaccurate.

You should aim for the least amount of annealing which will make the end feel softer when lightly filed.