Large overhead for consultants: agreeing to contract terms
Sometimes long contracts are required. Long term engagements can require more complicated agreements because more IP is shared and a consultant might need access to a customer's software and/or servers, etc. Anyway, I think that agreements should be as simple as possible but still protect both side's interests.
PS. While I was writing this, I paused, and decided to offer customers who use my NDA and contract a 12.5% discount. Anyway, I just updated my web site so it will be interesting how many people take me up on this offer over the long term.