It is a good idea to keep your accountant in the loop. A quick follow-up on documents you need to provide, but struggle to acquire, helps the accountant ward off nasty surprises.
The IRS loves to drag its feet when it comes to getting its paperwork out, but gives you 10 days, or else. The 10 day expected response is not hard and fast. You do need to keep the IRS informed of the timeframe for getting documents in. If your accountant knows, he should contact Revenue for you.
When pursuing an Offer in Compromise, I recommend you meet the 10 day window the IRS demands. If you don't, they will likely reject your offer and you will need to start all over again.
I know this is frustrating, especially when an IRS auditor demands documents within 10 days and then sits on them for three months. I never said it was fair; I'm just telling you how it is.
Besides, in most cases, there is no good reason to delay. The faster you get a resolution, the faster you get your life back.