Yithro's perspective versus Moshe's
In the words of the verse (18:22) Any great matter would be brought to you [Moshe] and every small thing, they will judge themselves. My grandfather points out that the formulation Moshe presented was somewhat different In verse 26, instead of referring to a great matter to be brought to Moshe, it refers to a matter that is difficult for them. Later on, in Parshas Devarim (1:17), the reference again is to difficult matters. Moshe says, "vehadavar asher yakshe michem takrivun elay."
Furthermore, Moshe deliberately equates great and small matters in saying "kegadol, kekatan tishmeu." As Rashi writes. based on Sanhedrin 8a, "yeheh chaviv alecha din shel pruta kedin shel meah maneh." [a judgement over a small coin should be as important to you as a judgement over a hundred coins of greater valu].
That was Moshe's view: a case doesn't become more important because it involves a larger amount of money. Accordingly, the escalation of the courts wouldn't depend on the sums invovled. It would only depend on how difficult the legal questions invovled were.
Related posts: http://kallahmagazine.blogspot.com/2015/10/dvar-yehudah-parsha-points-from-my.html