Cannot include navigation in single posts

what do you want to do different than what Twenty Eleven does already with the code in single.php:

<nav id="nav-single">
						<h3 class="assistive-text"><?php _e( 'Post navigation', 'twentyeleven' ); ?></h3>
						<span class="nav-previous"><?php previous_post_link( '%link', __( '<span class="meta-nav">←</span> Previous', 'twentyeleven' ) ); ?></span>
						<span class="nav-next"><?php next_post_link( '%link', __( 'Next <span class="meta-nav">→</span>', 'twentyeleven' ) ); ?></span>
					</nav><!-- #nav-single -->

It’s very confusion when a single post is presented outside the cycle in which the posts belonging to a category are arranged.

In my case, single posts were presented differently from posts in categories (although ALL the posts are in categories).

To counteract this I included the category name above single posts and confined “next” and “previous” to only navigate in the category to which a single post had been assigned to.
But “previous” and “next” needed more options like “page 1 of 1” because it felt too limiting.

I then found a function (above link) that works for category.php but not for posts generated with the singles. Now the challenge is to get some consistence between category- and single posts navigation.

alchymyth, do you understand what I mean?
The navigational style described above (before alternative solutions were introduced) is how it ended up to be in my child theme.
Although I realise Twenty Eleven comes with its own navigation solutions I just needed a little more. It’s important to note that I did not do away with it either but the idea was to build on it.
Anyway I hope I’m not being too particular. If I should be posting this in another forum, please let me know.

@alchymyth, maybe I haven’t yet responded to your question:

what do you want to do different than what Twenty Eleven does already with the code in single.php?

I needed a way to show navigation options more explicitly.
The navigation I used not only shows “next” and “previous” but also includes “first/last”, as well as a numeric pagination 1,2,3 etc.

I have tried to explain this elsewhere on the forum. The original OP question was:

How can I set ONE template to be used for ALL posts – such as category.php instead of using multiple ones?

I don’t understand the need for the single template. I guess I need a more static feel. Although I got navigation working for the category posts only, the real issue is that single posts seem to fall outside the cycle.
Do you know what I mean?

I certainly don’t expect answers relating to custom navigation implementation but it would be beneficial to learn more about the inner workings of that “cycle”. And I realise there’s a semantic difficulty in describing this to someone, my apologies. It would be more reassuring to know that the cycle issue is real than simply solving the navigation.