I am a senior with diabetes so my ED problems may not be relevant to you younger guys. In addition to reduced circulation due to age and diabetes, I also have low T. I have been battling ED for over 15 years. I have used Viagra, supplements, TRT, and pumping. You name it and I've probably tried it. The above practices help and can sometimes generate a 9 EQ erection, but I can not maintain it for more than 5 minutes. The only thing that allows me to have a satisfactory erection capable of sustained penetration is a constriction band around my unit. Here, again, I have tried all kinds of cock rings and constriction devices; however, the most effective constriction which produces the hardest erection is a doubled over 1/2 inch rubber band (bag of 50 for $2.95).
Because of my other ED issues, I need to take a Viagra (I also have good success with an otc suppliment - Maxidus) to get it up and then apply the doubled over rubber band (stretched out a number of times before first use so it's not too tight) around my whole, well lubed unit (behind my balls). It maintains a 9+ erection, slightly engorged (even fatter if I pump first) which I can use for up to 30 minutes before I need to release the band to refresh the blood supply. If I want, I can reapply the band and go for another 30 minutes.
I mentioned to my Urologist that I suspected a venous leak; however, he stated that he could do a doppler ultrasound to confirm the leak, but If I did have a venous leak, the basic procedure I was using would be an appropriate procedure to overcome the effects of a venous leak (short of experimental drugs currently being studied).
I have now resigned myself to the fact that I will never be able to achieve a spontaneous erection, but I can live with a 9+ erection with a bit of pre preparation not to mention that I can enjoy some great oral while I wait for my preparations to take effect.
If you young guys can get it up without Viagra, you may want to try constriction to keep it up.