"except for a period" is a correct and usable phrase in written English.
It is typically used to indicate that something is true or applicable except for a specific time period or event. Example: "I love living in London, except for the period of winter when the weather can be quite gloomy."
He said that conservation studies and treatment took place without restricting normal visiting hours of the tomb except for a period of one month in 2016.
Except for a period after World War II, when he was confined in St .Elizabeth's Hospital in Washington, D.C., Ezra Pound lived outside the United States after 1908.
Except for a period of British occupation during the Revolutionary War, Friends have met in this place every Sunday for more than three centuries.
Except for a period of 12 months — after Mr. Obama had blocked it in late 2015 and before Mr. Trump was elected — Keystone XL has been all-consuming.
In 1396 the Vidin kingdom fell to the Turks, who ruled it until 1878 except for a period of Austrian occupation from 1683 to 1690.
He remained as head of the party until 1984, except for a period (1954 58) when he was replaced by Dashiin Damba.
The biggest loan, extended so that the warehouse could buy unshelled peanuts for its sheller, was continually short of collateral "except for a brief period" in 1975, the report said.
(This is the same as it ever was, except that for a period of time, Ryan was amenable to the Senate's awfulness).
As we've shown, except for a brief period about 1989, in the postwar period capital gains have always been taxed at less than the top marginal rate on wage and salary income.
Except for a brief period about a month ago, and for reasons of Manning's own physical safety, Manning does not sleep naked.
