Well, the two days are just for interviews. So we have a lot longer to go through things and we send over a big laundry list info request before hand. But you're right, it's never enought time to be able to say "we found all the debt". It's definitely enough time for us to find out a lot about their debt, and this is always worth it to the acquirer (these are mid to late stage acquisitions, so typically over $100M).
Also, you'd be surprised how much we can find out. We are talking directly to devs, and we're good at it. They are usually very relieved to be talking to real coders (e.g., I'm doing a PhD in music with Scheme Lisp and am an open source author, most of our folks are ex CTOs are VP Engs) and the good dev leaders understand that this is their chance to get more resource allocation to address debt post-acquisition. The CEOs can often be hand wavy BS'sers, but the folks who have to run the day to dev process are usually happy to unload.
Also, you'd be surprised how much we can find out. We are talking directly to devs, and we're good at it. They are usually very relieved to be talking to real coders (e.g., I'm doing a PhD in music with Scheme Lisp and am an open source author, most of our folks are ex CTOs are VP Engs) and the good dev leaders understand that this is their chance to get more resource allocation to address debt post-acquisition. The CEOs can often be hand wavy BS'sers, but the folks who have to run the day to dev process are usually happy to unload.