Farming efficiency of outdated plots

Assume you choose to plot 4TB on a slow CPU. After some time the plotting has finally completed but the network grew by a factor of 3 in that time. Will the farming efficiency of that plot be 1/3 (before replotting)?

What triggers a sector to start replotting explains how plots expire, if you are good at probabilities you can compute what fraction of the plot will be still not expired by then.