The activation procedure is tedious and cumbersome. The zinc-copper couple is labile toward oxygen so it can be stored only for a limited time when reproducible results are to be achieved. Commercicially available zinc can be activated without the need of copper, similar philosophy can be used for the activation of magnesium for the grignard reaction[1]. Bench top zinc powder are heated to 140-150 C with vigorous stirring for a minimum of 3 hours under an inert atmosphere (N2), this is sufficient to activate it. Neither prolonged heating (overnight) nor higher temperatures (170-180) improved the yields or the rate of the reaction significantly.
[1] Baker, K.V., Brown, J. M., Huges, N., Skarnulis, A. J. and Sexton, A., J. Org. Chem. 1991, 56, 698.