On some occasions I allow the students to use pumps and extenders for a substantive period of time, the results were disappointing. In addition, I have been active in PE since around 1980, during those decades I tried everything available including all pumps ever made, manual exercises, all manner of extenders, and more currently the device that uses an elastic belt loop attached to a rubber sheath on the penis, again. This was very fortunate experience for those decades because it gave me essential experiential knowledge on everything available for my students. As a scientist and as an extensive PE practitioner I know what reliably works reliably well, what kind of works and is iffy, and what does not.
As mentioned, it is a scientific fact in order to induce collagen remodeling one must reach a critical threshold of traction starting at 8 to 10 pounds. The other devices simply don’t do that , extenders only produce a force of approximately 4 to 5 pounds and  at  best  can deliver newbie gains of perhaps1/2”-3/4” by pulling the waves out of the collagen, but falls short of inducing collagen remodeling..  Pumping can be used but there is a special skill that one must develop such as using a variable vacuum spiking scenario resulting in a pump stretch dynamic. Those who are not experienced in pumping  improperly  bring it up to maximum which results in edama  and  temporary bloating,  unfortunately no  significant permanent gains occur in the majority of cases. I can teach students how to properly pump, and it can be used as a viable instrument in one’s repertoire of instruments for PE.
I am often the recipient of disappointed students who have tried various devices. I explained to them the experience and the scientific basis for why we use The LG Hanger.  This is why we prefer traction devices and also a “special” pump that enables variable a vacuum scenario… Manual exercises are a useful secondary tool to the mechanical traction.