Here are some examples of use of utmost in contracts on EDGAR:
… provided that the party so affected shall use its best efforts to avoid or remove the cause(s) of non-performance and observance with utmost dispatch.
A Seller’s agent or subagent has the following affirmative obligations: (1) To the Seller. A fiduciary duty of utmost care, integrity, honesty, and loyalty in dealings with the Seller.
Landlord’s Broker owes duties to Landlord which include utmost good faith, loyalty and fidelity.
The Participant acknowledges that his position with the Company was one of trust and confidence because of the access to the Confidential Information, requiring the Participant’s best efforts and utmost diligence to protect and maintain the confidentiality of the Confidential Information.
Company will make reasonable efforts to ensure the utmost in content availability based on its existing relationships and contractual partners.
In all but the last example, utmost is apparently meant to turbocharge a given standard, but it’s not clear how it’s meant to work. For example, how does “utmost good faith” relate to just “good faith”? I say that in this context, utmost is invoked as pointless and confusing rhetorical emphasis, and I say the heck with it.
In the last example, utmost serves as an example of how vagueness is problematic when it’s not linked to a reasonableness standard. (See this 2012 post.) This use of utmost is analogous to substantial. How much content availability (great, an abstract noun) is “utmost” content availability? I have no idea.