The lack of interdisciplinary collaboration is one of the major flaws of the US university system (I can't speak to other countries). The grad students I knew

The lack of interdisciplinary collaboration is one of the major flaws of the US university system (I can't speak to other countries). The grad students I knew each had a specific toolkit that they had learned in their field but there was little or no sharing of those toolkits from domain to domain. That is unfortunate. Of particular importance in today's world are a toolkit of mathematical techniques (calculus, statistics, differential equations are probably the top three categories) and a category of basic programming skills (the ability to automate routine number crunching in particular, maybe "scripting" is a more appropriate word than "programming" - even recording and writing macros in Excel VB would go a long way).