Since greggiis are woody and stems are long-lived, it may be a time for shaping and thinning a bit, but I would not cut off more than the flowering stems. They will dry out into thin dead twigs and don't interfere with the plant growth much.

Cutting back after spring flowers is more appropriate for the basal rosette meadow sages and to the subtropical fleshy stemmed sages to a lesser degree, mostly to control height and shape. I would not hit the subtropicals hard.