Hola Gabe!
When we talk about sunshine and light, we have to also talk about water and watering so here goes:
Sunshine helps bring out their colors better, and it is still a plant that needs sun to do its food, though the stomates are closed during daytime to conserve water, that is why it is so drought tolerant. At night the stomates are open so more biochemical reactions happen, that is why growing them outdoors is best for these plants.
During heat wave days, it helps to put them in part shade, too much direct sun really dries them way too much and colors will suffer just like any color that gets sun bleached when left in too much sun. So getting them part shade area is essential.
Morning sun is okay it is still cool in the mornings, it is the afternoon sun that is really so intense so see where the orientation of the sun is and put your plant maybe under the shade of another taller plant or shade of a furniture or bigger rock.
My plants get only part sun-part shade too, actually like more shade since my garden is shaded by our house in the morning, sun overhead finally gives them some direct sun at noon time to 2pm, and gets dappled light in the afternoon when the sun is to the west and city trees cast shadows on my garden. But heat is blanket very dry heat, so have to water them a bit more early in the morning since evaporation is very fast, aiming the water direct to the soil so the roots can be kept cool and drink ahead before the heat envelopes the plant. It is just too dry here. Then allow to drain and dry out before watering again.
In my area, my semps look better in late Fall to mid Spring. After that it is survival of the fittest during summer time because of our intense heat.
