How have the courts apportioned the expense of calling evidence for warranty and misrepresentation at trial?

As regards the witnesses: To paraphrase the language of Aikin, L.J. in Christie v. Platt, supra—Did the plaintiffs incur the expense of calling evidence reasonably with a view of supporting its claim for balance of purchase-price? Or, was the expense incurred really to meet the issue as to warranty or misrepresentation? If the latter, the expense was not properly attributable to the claim. If it was incurred on both counts it should be apportioned between them. And in taxing the defendant’s bill, did the defendant incur the expense of calling evidence reasonably with a view of supporting solely the issues on which he has succeeded? Or, was the expense incurred really to meet the issue on which the plaintiffs succeed? If the latter, the expense was not properly attributable to the defendant’s claim; if it was incurred on both issues it should be apportioned between them.