I think in the RCC, you can be as involved as you make yourself to be. There are many small ministries, and you can meet people that way, and then when you see them in church you say hello and connect. But, you could also go and come for years and years without ever knowing anyone. The only way the church would ever know you were sick, etc...is if you contacted the rectory. No one would notice your absence. Also, there are several Masses each weekend, you might go to a 4:30 one week, and the next week, a 9:00, seeing a whole different group of people. And now it is a larger group because churches are closing and combining with other churches in the area.
When you do the above for years, it is different to have someone ask, "where are you going?" ( Huh? Are you speaking to me? lol) It is nice though, too. I think that is the way the early church was. Once you get that mindset, it is easier to understand. It does involve getting to know others, and have them know you.
I am also more familiar with a one hour service max., and now I am there almost two, maybe more. Sometimes, I prefer the walk home right after, we don't live far from the church, and on a nice day, that time alone to think about God and the service has been so nice.
So, maybe the best bet all around, is to pop in every now and then, if one can't or doesn't prefer to go each week after service. Just didn't know if I was doing something very unconventional by leaving.