I find it a lot easier to reason about logical chunks of code that are clearly divided. I rarely want to see just a specific function, but a cohesive unit that can be read in sequence and make sense. You can do that in a single file too, but in my experience, large files tends to lead to code being spread out without a narrative determining order because people (myself included) are rarely disciplined enough. Files act as a convenient clear grouping to me. On the other extreme, when people insist on splitting everything up into the smallest little unit, it drives me entirely nuts for the same reason. I want to be able to read through the code without jumping back and forth all the time.

But when it's just you it's all down to preference, so do what works for you.