Name range that will change size multiple ranges

I have multiple ranges seperated by a blank row. I want to name each range to use in a formula. The ranges will change when I insert new rows. I want to name each range I3:I22 as Hrs1, K3:K22 as Cost1, then I24:I39 as Hrs2 and K24:K39 Cost2. Then if I add two invoices to my first named range, I want the range to expand to have Hrs1 be I3:I24, Cost1 be K3:K24, Hrs2 to be I26:I41, Cost2 to be K26:K41 etc. I'll attach my example.