I’ll lay down my thoughts on internal link optimisation later in this seo tutorial, but onpage, I link internal to relevant pages in my site all the time.
I silo any relevance or trust mainly though links in text content and secondary menu systems and between pages that are relevant in context to one another.
I don’t worry about perfect silo’ing techniques any more, and don’t worry about whether or not I should link to one category from another, as I think the ‘boost’ many proclaim is minimal on the size of sites I manage.
Sometimes I will ensure 10 pages link to 1 page in a theme, and not reciprocate this link. Other times, I will. it depends on the PR google juice I have to play with and again, if it feels right in the circumstance to do so, or the size of the site and how deep I am in the structure.
There’s no set method I find works for every site, other than to link to related internal pages often and where appropriate – it’s where I find some creativity.