(1)    Except as otherwise provided in sub. (2) or elsewhere in chs. 401 to 411, the effect of provisions of chs. 401 to 411 may be varied by agreement.

   (2)   The obligations of good faith, diligence, reasonableness, and care prescribed by chs. 401 to 411 may not be disclaimed by agreement. The parties, by agreement, may determine the standards by which the performance of those obligations is to be measured if those standards are not manifestly unreasonable. Whenever chs. 401 to 411 require any action to be taken within a reasonable time, any time which is not manifestly unreasonable may be fixed by agreement.

   (3)   The presence in certain provisions of chs. 401 to 411 of the phrase “unless otherwise agreed,” or words of similar import, does not imply that the effect of other provisions may not be varied by agreement under this section.