From what I remember, it was Jack O' Lantern that the new system was introduced and where we saw all this start.
That being said, you don't always get 3 Reds doing Solo, or MVP-ing your own Raid. I've had many occasions where I have only gotten 2. When you Start and MVP your own Ragnarok you get a chance to get dropped the 3rd Red, you also get a Drop that has a chance to give you an SR/SSR or another Ticket. From what I have seen this is the only way to get SR/SSR drop (Start your own and MVP it are the prerequisites). I have not seen anything that has disproved that theory. So if you do get an SR/SSR drop when you didn't MVP your own Ragnarok I would love to hear about it (because naturally people are going to want to prove me wrong, so I'm asking for it ahead of time.)