When you look on somebodys profile on FB, and at the top of their wall it has "recent activity", how long ago, or recent does that mean? In last week, month??
When I peruse my 'friends' posts it looks like the recent activity is collated to show:-
What they've posted, friends confirmed/requested, etc in the past 24 hrs
if outside of that period it is what they have done in the past week, and beyond that it's the posts, friends made, things liked, etc in the past month, then probably year.
If you're on someones profile you can just keep clicking 'older posts' at the bottom. I was able to go back to a year ago recently on a family member recently which was very helpful in getting some clarity on a situation.
I don't really understand the difficulty. If I got in to my own profile I can see all the status's and comments I've made and the time. If I click on a friends profile and see they've made a comment on someone elses status then I just click on that status and it tells me when they made the comment...So now I know that one of my friends wished a member of her a family 'happy birthday' several hours ago!
I'm not quite sure why you're finding it difficult. Maybe you just need to play around a bit more.