Way back in 2009 Buzz Burrell, Jared Campell and Ryan McDermott completed Imlay, Heaps and Kolob canyons in just over 25 hours. 
Zion Trifecta | Adventure Running (wordpress.com)Zironman Trip Report Pt 1 (article on completion is pdf at bottom):  https://adventurerun.wordpress.com/2011/11/13/zironman-pt1/
We did many big projects, more on the summits than in the canyons.  Here’s two examples:
https://adventurerun.wordpress.com/2008/10/20/zion-double/
https://adventurerun.wordpress.com/2009/04/16/zioneering/
Contacting Buzz: Podcast:  https://news.ultrasignup.com/the-trailhead-podcast/
Facebook:  https://www.facebook.com/buzz.burrell.14
The Canyons are Calling Podcast | Facebook  To follow me on Instagram: The Canyons Are Calling (@canyonsarecalling) • Instagram photos and videos To become a member of my Patreon community: The Canyons Are Calling is creating Podcast | Patreon Background music by Chris Zollinger Steel Drum | United States | Z The Handpan Man Intro music by Tig Booth nathaniel.booth@gmail.com My website thecanyonsarecalling.com has more information about each person as well as links to other canyon resources. If you would like to be a guest on the show or know someone that would make a good guest reach out to me at thecanyonarecalling@gmail.com The canyons are calling. Let's go!