My observations after following the express entry rounds since early 2017. I already am a PR but still follow the lists some as my friends are in the waiting still
I got my PR in 2017 April at 457 (cutoff was 431, I had created my profile only that week) points, that same year my brother got his with 439 points and cutoff went as low as 413 in May 2017. In June 2017 CIC changed the point system. After the change, lowest cutoff in remainder of 2017 was 433. The draws were of random numbers anywhere in high 2000s to nearly 4000.
2018 is when the bi-weekly draws became of fixed numbers. That year, despite having higher invites, cutoff was lowest at 439 in the very last draw of the year. A couple of times at 440-442, as if to keep a circuit breaker, CIC skipped one week in the draws to keep score above 440.
In 2019, January 30th they released B2B draw after 23rd Jan with 438 points. (True story: A very close friend of mine who was at 438 got the invite. His birthday was next day on 31st Jan where his score would have dropped. He now has his PR and is flying out in October. He got through because of a random B2B draw one day before his birthday with cutoff exactly what he needed. I see that as destiny and a nearly a miracle) Since then, the score has kept above 450, and on May 1, when it touched 450, circuit breaker was put and next full draw came on may 29th. Not to deflate anyone's confidence, my guess is CIC will let scores drop to 450 odd this year too but may not want to go much lower. I'll recommend anyone below that to try and increase their scores. I have another friend waiting at 445 and though I'm hoping, I still fear he may not get through before his birthday in March.
430 odd seemed to be the benchmark score in 2017, 440 in 2018 and 450 in 2019. A lot, and I mean a lot of people are now aware of and are applying for Canada than a couple of years ago, that's for sure. So try to maximize your score to counter increasing number of applicants and a possible CIC benchmark.
All the best to everyone waiting for their turn!