You can usually run much more than specified.  The limiting factor is physical clogging of the column, so you'll see when it stops moving through.  It's hard to predict when exactly that happens, because it depends on characteristics of the particulates and polymers in your sample.

Thank you both for your answers! I ended up doing a bunch of Maxi Preps but I'll certainly give the Midi Prep route a shot next time given some ballpark figures for the capacity of the system.

The health of your culture and the amount of lyzed biomass are critical factors to obtain a good amount of pure plasmid. My advice to you: forget about the DIY kit option! Send us your plasmids as we can prep them for less than it takes you to do it. We typically obtain better results than you would with a kit in terms of DNA quantity and quality. See for yourself at https://www.biozilla.bio/plasmid-dna-purification