Ok then.
English is not my native language so i am not sure that i understand correctly what you say.
I don't know how it is possible to stretch with a grip at the base. I mean that if you do that the whole shaft remains without tension and you basically stretching your skin. Gripping the glans is the most effective, because its the only way to prevent skin stretching. Also the tension is transferred to the whole penis smoothly. Gripping at mid shaft, again you dont target the whole tunica and there is some skin stretching involved.
If you are a manual stretcher maybe you have realise that you cant hold the stretch enough time with the OK grip because your penis slip. Instead face your palm, rotate it and place your penis(just under the glans) to the space between your index finger and your middle finger and stretch. Like the V sign(peace).