Thankfully they have lessened over the years. They started out every half an hour around the clock and lasted 10-15 minutes. Now it's depends on the temperature outside, and in the house. I get them every couple of hours and they last about a minute or two. Just enough time to complain and find a fan. Thankfully my husband doesn't mind a cooler house. Not that he has a choice. They also can trigger nausea and nerve pain. I'm still here. That's what I try to focus on.
Funny thing when I asked my oncologist about them ever stopping his first answer was a year or two, the next time he said 5 years, the third time he said 10 years, and than added possibly never. I guess he wanted to work his way up to that answer.