Being able to access individual time logs in a single record would allow the ability to, for example, invoice for time that was logged to a single record but spanned across billing cycles.

Let's imagine that I'm working on a multi-week project, my billing cycle is twice per month, I've invoiced for the first two weeks and now I need to send an invoice for the second two weeks.

I would need to be able to differentiate my time logs, rather than just using the total amount of time logged - especially considering I may have already started logging time for my third billing cycle.