Hi th1996,
The reason for engaging in tantric sexual practices such as pre-orgasmic sex (no ejaculation, no blocking) is to avoid losing prana during sexual activity. This prana can then be used for spiritual purification. So, the main purpose of tantric sexual practices is not to increase pleasure during sex, although that can be a natural byproduct for some people.
If you are still blocking after ten years, then that could well be because you keep choosing to do that. Most men can choose to stay away from orgasm and avoid the need to block, especially with a bit of practice. If you are choosing to reach orgasm and to block often, then you may not be at the maximum level of progress because there is still some energy loss even with blocking and even if shambhavi mudra is used.
But it is not an all-or-nothing process. Some men experience a build-up of energy over time and may need to release once a week, or once every two weeks, in order to avoid this happening. How often it is, will depend on the person. As you have noticed, there is a loss of spiritual energy for a day or two after orgasm, so releasing too often can impede progress whilst not releasing often enough could also impede progress.
As for the enjoyment aspect of pre-orgasmic sex, this depends a lot on the state of purification of the energetic channels in the body. If the nadis are pure, any sexual activity will bring the body into a state of ecstasy and we can ride that ecstatic wave during sex whilst staying well away from orgasm. This wave can deepen to be much stronger than any orgasmic experience and can last for many minutes, or even hours.
Gradually this full-body ecstasy is present whenever we meditate as well, or whenever we practice pranayama or asana. Eventually it is present during the day as well, whatever activity we are doing and even whilst we sleep at night.
So, it is a gradual process that evolves over many years, but staying in front of orgasm is an important part of it. Will the process of liberation happen anyway, even if someone does not stay away from orgasm and is blocking often during sex? Maybe, or maybe not. That would depend very much on the person. It would certainly take a lot longer.