I use this one (perhaps the only one in this forum) and it lasts for 2 to 3 hours. Generally, I see no drop after 150 minutes as max. and by the 3 hour mark it is almost out of my system. NovoShitty keeps dropping me after even 3.5 hours so I quit on it because I found it very impractical.
I pre bolus only for brealfast and for 5 minutes only because I am pretty active.I’m on Humalog too. However, I would say it is still working after 4 hours on me, albeit not as rapidly as the first two. I pre bolus and it certainly doesn’t have an affect for the first 30 minutes. Line on the Libre doesn’t move.