Blissey more effective at lower CP?

Yes, it's a pain to fight. And prestige too. But if you have friends from different teams you could place a crap 'mon below the blisseys, prestige against it, then have the friends kick it out and go do the same for their gyms. Would work fine in a city with plenty of gyms to go.

I agree. I find the best place of Blissey to be around spot 6/7/8. This way the attacker has either the choice to fight the Blissey or chicken out early, but only dmging the gym with a small amount compared to when she was at place 2 for example.

This is in agreement with an old article I read some time ago on reddit (?).

I think this is true, but it has some issues. You wouldn't want to place blisseys near the bottom unless this would finish filling up the gym, because otherwise knocking off the bottom pokemon would make it too hard to prestige. Also, in areas with a lot of gym shaving, people don't really like intentionally taking spots really close to the bottom. Otherwise it's a good idea.

While I agree that having Blissey near the bottom is better than at the top spots I think you should take into consideration that if the gym gets attacked and goes does for example from 50k to 43k, then your team would have to prestige against that 2-3 Blissey in a row that you mentioned, making it too hard for almost any player, and once that gym is 43k for too long it is more close to be a level 0 than a level 10.

Let me explain, just based on my experience, at least this is what happens in my town, if a gym with some prestige left is not going up in a few days (let's say 2-3 days), then it won't last at all no matter what level it has, it will be down fast.

I think that seeing a gym without activity despite having prestige left makes other teams try to go for it, the reason behind could be that other teams will think that the gym will keep having zero activity once it is on their team.

So giving that prestiging efficiently is as important as having a good gym, I would say that those Blisseys should be more in the middle of the gym, like position 5-6-7, instead of 2-3-4, that gives room for prestiging even if someone takes down the gym 1-2 levels.

I totally agree. Blisseys make gym stronger when they are in the middle spots. A Blissey on the top is almost useless because you can skip it every attack making it faster to take down the gym.

Again, this is all dependent on your gym CP area and my thoughts are based on mine...My area is all near 2900 and a lot are over 3000+ now for a bottom spot. You really need to be over 3100+ now.

The Blissey near the bottom thing has always been true, but remember that Blissey still has the 6th highest max CP so eventually and quickly if you have gym shavers in your area, it will naturally find it's spot near the bottom of a gym...

I've maxed all my Blisseys (3000CP+) and one is hanging on to dear life near the bottom of a gym.

With common Rhydon, Garys, Dnites (common in eggs now), I think it's simply better to just keep them maxed because they will be near the bottom in short order.

Leaving them at 2700 or whatever means you will get kicked out first in my area so max away IMO...(again, all dependent on gyms in your area).

I think best place for blissey is on 5-7 in a level 10, also multiple blisseys with other defenders in between really strengthens the gym