Chitting - How Big Can or Should You Let The Chits Grow?

Up to an inch is about right, but more important is that they are sturdy and green/purple in colour.

Pale chits are a sign of insufficient light, and although it sounds paradoxical such chits would slow down if given more light (if they are really long and white it's better to rub them off and start again even at this late stage, as they will be weak and break off anyway when you plant them.)

Thanks.
They are a bit longer than an inch but they are nice and thick, purple with green fronds developing (It's "Home Guard" for a change this year).