A small downside with some taller Sedums is that can be lax in habit with plants not standing upright, which can cause a bald centre.
This can also be a problem when Sedums are grown in too much shade, or rich soil. To avoid this, pinch out the plants to make them bushier or by using the Chelsea chop in late May or early June. Cut top growth by around 10cms, don't throw cuttings away because it is easy to propagate new Sedums from these clippings, see below. Nipping back stops the floppy growth and makes for a better-behaved plant.
This can also be overcome by selecting a variety of Sedum which will do better than others. I do not find this problem occurs with Ruby Glow and the RHS garden merit award varieties tend not to do this. Also, the shorter varieties have a more upright in habit. Although Sedums really are a good egg of a plant, (loved by pollinators and butterflies, low maintenance, easy to grow, flower reliably and more,) there is this one possible problem with some varieties of Sedum as shown in the image.
If you have a Sedum which does this, you can either trade it in for a newer model as many of the newer varieties do not do this, apply the Chelsea Chop earlier in the year, or stake it.