My experience with my Santana, bought in '81, has been with my wife, a female club rider, my daughter and my son.
My wife makes me work hard. I find that if I decide to stop pedaling without telling her I don't get any reaction to the pedals. The friend from the club will rip my feet off if I don't let her know I'm gonna stop pedaling and we have had some very fast rides without me working as hard as with my wife. My daughter, a young teen at the time, let me pull her and I worked hard. With my son, about 11 or 12 at the time, I felt like I had a small engine on the back of the bike. A very good power to weight ration with him and we could stand on the hills with no problem. I didn't have to work as hard with him and we did centuries with no problem.
I've only recently pulled the tandem out of mothballs and have been riding with my wife. I still work hard with her.
My granddaughter is coming of age to ride and I'll be putting the child stoker unit back on for her very soon. I'll have to wait and see if she pushes her own weight!
If you're working hard on the hills and the stoker can jabber away then he/she isn't working as hard as you.