Views output into multiple columns based on variable of results Scenario:
I want to output a 3-column display, i.e. first 5 results on left column display, next 5 in middle column, last 5 on the final column.

I can do this with a fixed amount of results using different views + offest, but I want to do this with one view with a varied amount of results:

e.g. 
Col-1: 4 items
Col-2: 3 items
Col-3: 3 items

Example is iTunes website:
https://itunes.apple.com/au/genre/podcasts-technology-tech-news/id1448?mt=2&amp;letter=X

They even account for pagination
https://itunes.apple.com/au/genre/podcasts-technology-tech-news/id1448?mt=2&amp;letter=T

What would the best way to approach this? Would you need to get a count of results then set the offset for the 1st, maybe 2nd column if it's not a divisible number?
not sure what you're asking is really possible just through the Views UI.

However, this should is reasonably simple with a views template file and a bit of PHP knowledge.

http://webpartners.es/en/drupal-7-views-templates-and-preprocess provides some info about how to override the output of the view. you'll need to apply a bit of logic on how to begin/close your columns/lists but that's just a bit of arrays in PHP.