My main is remapped for per+wil. Clarity (rank 3, per+wil skill) increases perception by +1. I already have Spatial Awareness V and Clarity IV. The training would take almost 10 days. However, I'll be training per+wil skills for the next year.
According to my one year evemon plan, adding Clarity V will add 3 days to total training time. I plan to play eve over the next 2-3 years at least, and cross-train ships from all 4 races over the next year and beyond. So this might be useful in the far future. But then I'd have to wait another 10 days right now before training anything useful.