Gaining on PE requires much patience. Its a marathon , not a sprint. Relax and enjoy. But let me be more specific.
For me there are 3 main issues that u may dont gain.
1st. Not enough rest { by this i mean the whole process that ur penis tissues require to recover, this process is so diferent on ppl to ppl as it comes to biology too, ur physical stape (for examble increased blood rate effect by doing joging or running and some healthy foods helps bring to ur penis the nutrition it needs to heal faster), ur psychology - anxiety, not enough sleep and so on}. PE is like athletism, a good health is required too.
2nd. U may dont do the excersises well and 3rd maybe ur penis is not just ready on some intense excersises. A very strong strech with ur hands till u feel exhasted doesnt mean that u really strech the tissues*.U must " feel the strech". A good warm up, keeping anxiety away , trying to relax finding some privacy too will result on relaxing the tissues so u will be able to strech more without using much effort with ur hands. Just try to strech slowly till u "feel" the "strech" u must not feel pain , just a pleasant streching feeling. Its better to do an efficient little number of streches feeling the strech rather do a lot pushing too hard with ur hands. Just as u gain expirience u will be able to strech harder and put more intense routines and excersises, but this has only to do with u and ur penis, we r not all the same. Try to "hear" it and feel it, dont do the excersises like doing a must to do homework, u must enjoy with the excersises and feel good too.
* if ur penis isnt trained enough on PE, by streching with intence force ur penis has a mechanism to prevent this sudden force by just doing the opposite u are trying to do. (Its the inertia phenomenon too). So u strech hard and ur penis is trying to keep its initial state so the tissues are not streched at all.
Just dont rush things , take ur time, relax, keep anxiety away and u will see results.