2nd Contracts

This is more of a general question about roster building. Do teams generally devalue certain positions and are therefore unlikely to offer a second contact to a good player at such a position? For example, the Giants have had a run of really good DTs that they let walk after the 1st contract ended - Linval Joseph, Johnathan Hankins, and Dalvin Tomlinson. I've concluded that recent Giants regimes view DT as readily replaceable through the draft and lower tier FAs. With this in mind, I find it highly unlikely for the Giants to use more than 1 pick in the first 2 rounds on OL, with tackle being the slot most likely to be filled with one of the first round picks. When I read posts from people wanting the Giants to double dip and "fix the line" once and for all, it seems short sighted as the likelihood of extending all 5 linemen to 2nd contracts seems a pipedream - too much money invested in one position group.