I was going to post a query on the same issue. I have seven PPP that I put into flower about 3 weeks ago when they where 15 to 16 inches tall. The largest one is now 28 inches and still climbing around an inch a day. Although they all look healthy, I am worried that they are getting cramped in their 8 ft space. My lamps have another 2 1/2 feet of upward adjustment to them and I don't know if I should be worried about their height.
I am a first time grower, and was not prepared prepared for how rapidly these things are growing.
Are they going to continue growing at this rate until harvest? Or is this something that generally slows down after an inital burst of growth??
I'll start another thread on this issue as I havent seen it addressed elsewhere, and am curious as to how others have handled this.

Photos attached. In the last photo it shows how I have 7 PPP on the left side of the room and 5 White Widow on the right side.