I received a 1099-INT form from the IRS last year (2016) but have not gotten one this year. Is this something I should expect to receive yearly or just a one-off?

Just a one-off. 

Generally, you would receive a 1099-INT, from the IRS, if you amended your income tax return and had a refund.

The IRS may pay you interest if they send your refund later than 45 days from the filing deadline for your return. If you file your return before it is due, the IRS still has 45 days from the deadline - generally April 15.