I am altogether what you said. ... Wait, not the last one. Never just say "nice post" only. What I found out while I am on steemit is, that there is no strict way to act and react.
It is always a dance.
I do not load any "once for all" set rules on my shoulder. When ever I did that, I failed greatly and felt shitty afterwards. It simply doesn't work to follow a strict plan for me.
I do behave here more intuitively and comment as I feel, follow whom I find interesting, drop where I notice that one is repeating oneself or just let enough time go by to find anything catching me. Also I behave loyal to those who helped and supported me and give them my share.
What I find helpful is to let go of the thought that I might miss a good post. If it's good and I find it after the 7 day time window, than be it. I can comment it even it IS past the window. Actually I find it a nice surprise for the receiver commenting on an old article. Still there can be a dialogue of quality.
Sometimes I make a semi relevant comment, just to act nice and let the other one know, that I am still there and interested. A vote is sometimes not enough, in particular when I am already in touch with the user for quite a while.
For me it is as for all other users here: I like it a lot when I can see that a reader indeed engaged with my content and so I want to give that back. I guess sometimes I am brillant and sometimes I suck in commenting.