Nah, I use blood all the time. It CAN open a portal if that is your intention, but it won’t by itself, you still have to put the work into it. Especially if like me you already have strong natural protections and a bloody-mindedness you have to overcome to connect. Most portals are naturally temporary, they’re a kind of thoughtform, and will fade and close when not sustained. There are ways to make permanent portals, but you have to put a bit more effort in.
The effect of your awareness of bloodletting is that it will be attractive to entities in the vicinity, and to those that you reach out to, usually (not all of them like it, some are disgusted, so be aware of the preferences of the entity in mind - ghosts usually love it).
Once you have an intentional connection with a specific entity, and you offer blood for them and they accept, that starts developing a relationship, yes. It will help build that relationship faster and harder than without. It’s still a relationship and that still has to be maintained to be fully effective. There’s no real free rides in life, and not in magick, not of the kind you usually want, anyway.
As a woman, I don’t find period blood special at all. It’s a dying, waste product that you were otherwise going to flush down the toilet. Because I personally see it that way, it colors the energy I would get out of it and I would never use it in ritual - unless, I had a specific request for it.
Intention is everything, because you see at as special, that’s the energy you put into it and it helps make it special. You could use wine with the same energy.
Caveat: the fact that’s period blood is dying and may have started to rot can provide really interesting alchemy for necromantic workings, and as an ingredient in workings that combine many types of blood by design. It’s also true that fresh blood is dying. That giving up of life is what the entities I think want to consume.
If you want to made a blood offering of the highest quality, sacrificing pain and blood that is alive and would otherwise have sustained your life, that you don’t really want to give, that is where the power lies in blood and sacrifice. That’s what VK does, and that’s the energy he refers to when he says “blood”. If you’ve seen his shoulders you know how he does it, he’s pretty hardcore about it. But like me, I think he also likes it. The more emotionally contentious the area from which you take the blood, the more energy it has, and the quality can change slightly. Blood from the thigh feels different than blood from the fingers. But for most purposes, like anointing sigils, the difference isn’t a focus.