I was recently traveling to a few of my customers. Through these meetings, I realized that a lot of project delays we experienced are caused by cultural differences between our companies.  As a SaaS customer or partner, how often have you noticed cultural differences affecting project timelines or outcomes with vendors?

Cultural differences is a big term and could mean a lot of things.   At it's deepest level culture is about the unquestioned assumptions a group of people make.   These assumptions show up in values and then the practices and systems and norms.   

With Saas organizations the biggest cultural difference comes from the methodology.  Is one group interested in the creativity, autonomy, and moving quickly of an Agile methodology while the other more focused on a calculated, risk-averse, certainty focused waterfall methodology.  It may not even be talked about.   

Getting clear on norms and doing joint chartering to get on the same page is the best of many incomplete options of how to make this less bad.