Keep in mind that any corporate taxpayer of size effectively keeps two sets of books; one to satisfy IRS, and one for SEC and financial reporting. Differences (mainly re: timing of income and expense booking) between the two result in the creation of deferred tax assets or liabilities on the SEC books. Estimated tax payments relate to the IRS books, but the SEC books will reflect a provision for income tax expense), and it is here that there could perhaps be some useful information. However, I believe the current corporate tax rate is 35%, more or less, for income over $335K, so seeing a tax expense number in the neighborhood of 35% of Q2 income (not considering any loss carryforwards or other book/tax differences) would be expected and not very predictive about total income for the year, IMHO. Estimated tax payments for tax purposes are even less useful.
The above results from "channeling" a prior career, and I now have a splitting headache and must lie down, LOL. Perhaps Fut or Bush can clarify further.