To truly understand what Dean meant we would need to hear him and see his facial expressions. Within the context we have, I would presume that Dean knows this from lots of experience. He may have said "Highly researched, of course." with a hint of sarcasm in his tone. (meaning that he has no official research but still knows it to be true.) Several different meanings can be inferred depending on how it is said and where the emphases is on the words.

What you have written is correct. You may also want to add a reason for it being a waste of time. Other ways of saying it would be - It is not worth the time. It is not worth the effort Don't give yourself to a lost cause. It is a lost cause.

I was distracted. I was not paying attention. I was focused on something else. (I was focused on the invoices) you can preface all these with "sorry" ---------- Me había distraído. Yo no estaba prestando atención. Yo estaba concentrado en otra cosa. (Lo siento, me se centró en las facturas.) Puede prefacio todos estos con "lo siento".

Check out this video on Ser V Estar - https://www.youtube.com/watch?v=ixOPCv2UjVE#t=24