There seems to be a view that pumping or clamping in combination with other manual PE seems to work better than pumping or clamping along. This should not perhaps be surprising.
To start with, lets stick with pumping, as clamping is considerably less safe in general. Having said that, pumping and clamping are more-or-less achieving the same effect, I.e. A pressure difference between the tunica and the surface of the skin, so we can consider them together.
When pumping you are essentially ‘inflating’ your tunica, much like inflating a rubber tyre. Anyone who has inflated a rubber tyre will know that when the pressure is released it will return to *almost* exactly the same dimensions as before inflation. The same is true of the tunica. However, the key word here is *almost*. There will sometimes be some degree of permanent deformation, depending on the elastic properties of the tunica, the pressure difference applied, and the duration of application. I have seen some forum members state that the tunica cannot be permanently stretched like this, using Kevlar as an analogy. This is very misleading. The elastic properties of the tunica are very different to those of tough synthetic polymers like Kevlar for example. Indeed, the tunica is composed mostly of two bio-polymers, elastin (5%) and collagen (95%), woven in such a way as to create a durable sheath. These biopolymers, like other sinews in our bodies, can be stretched and permanently deformed with repeated application of stress.
So what has this got to do with pumping and manual PE exercises? In my view, the main benefit of manual PE like jelqes and ulis is to make the tunica more flexible. I expect they achieve this through warming the tunica, and creating a build-up of fluid within the tunica. All of these effects can be expected to make the tunica more deformable. It is well known that polymers are more flexible when immersed in a solvent or when subject to heat. This is because the solvent (or bodily fluids in the case of the tunica) help to lubricate the sliding of polymer strands over each other, and heat will always make any material more flexible (due to thermal motion and expansion). The forces imparted by jelqes are, however, not that high.
In contrast, pumping mostly creates a stretching force to deform the tunica. It migt also increase the build-up of fluid in the tunica.
So, by themselves, jelques and pumping might not be the optimal growth routine. That is, by themselves jelqes do not apply that much force (compared to pumping) to the tunica, and by itself pumping does not improve the flexibility of the tunica as much as jelqes. But when used together, it seems to me, they are very complimentary. The jelqes make the tunica more deformable, while pumping actually significantly deforms the tunica. With repeated application, I expect this can lead to significant and permanent gains.
Stretches, like hanging, apply the deformation force along the length of the penis to create length gains, while for pumping the force is largely directed radially outwards to create gains in girth.
So it seems to me that combinations of exercises involving jelqes, pumping and stretching are likely to lead to the most rapid gains. They are complimentary.