The U.S. Supreme Court has ruled that a person has a right to burn the United States flag; it is a form of expression guaranteed by the first Amendment to the Constitution of the United States.
The issue of flag desecration as a form of protest came before the Supreme Court in Texas v. Johnson, 491 U.S. 397 (1989). The Supreme Court reversed the conviction of Gregory Lee Johnson for burning the flag by a 5-4 vote. Justice William J. Brennan, Jr. asserted that "if there is a bedrock principle underlying the First Amendment, it is that government may not prohibit the expression of an idea simply because society finds the idea offensive or disagreeable."
So if I wanted to, I could burn a flag (in an appropriate place) every day of the week from here to eternity. That would be legal. The act of burning the flag is a legally-protected form of "speech."
I have been protesting my job termination for the last eighteen years. Somehow this arouses the ire of people. "You've been at this for 18 years? You need to get on with your life." The fact is I am permitted to protest my job termination by any lawful means -- for any time period. If I want to protest my job termination for the next 20 years, I have that right, so long as I use lawful means. My obvious anger toward my former employer does not mean I am potentially violent. My protest against my employer does not mean that I might commit a violent crime.
If I had stuck to burning the flag for the last 18 years, maybe no one would have noticed. But if I protest an unlawful job termination for 18 years, people start to worry. Now that's a legal irony.
But remember the words of the U.S. Supreme Court: if there is a bedrock principle underlying the First Amendment, it is that government may not prohibit the expression of an idea simply because society finds the idea offensive or disagreeable.
There's no statute of limitations on the expression of an offensive or disagreeable idea.