To be honest, I rough guessed the 1.1 part. I do have over 20 years controlling and I've been on the receiving end of someone launching a DC9 when the previous Cherokee was 2.5 miles from the runway, both on runway heading, and I'm not talking to the Cherokee yet! I have worked in VFR towers with and without RADAR/DBRITE. I have Center time and approach time as well.
I also try to stay in the shadows on most of these threads until something begs for a comment...
It is too bad I can't provide the tapes from about 1 year ago when I was the local and the radar controller combined and my supe was the fd/gc. I was clearing a plane to TIPH seconds after I cleared the previous a/c for takeoff, and then turned the a/c that I launched, BEFORE that one, away from runway heading, and then cleared the next for takeoff, then TIPH,... you get the point. Most pilots said little more than "Roger" and they'd do exactly what they were told. It was an awesome group of pilots, all flying g/a, the only aircarrier was the opposing team. Almost every one said "great job" or "excellent work" when they left. They really made the job FUN! This blows away simulators!
Ry length= 7001, vr=150, distance to vr=3600, time to vr=25 secs(roughly), interval for next plane=45 sec, roughly 90 airplanes per hour departure rate. A little high but can really mess with approach control! Stop departures.