Staggering rounds in a shotgun or having different types of shells loaded into the tube/magazine is not a good idea.
For a defensive shotgun or any shotgun that has a specific role or purpose, it should be loaded with the most appropriate shells for that task. Any specialty rounds or different rounds (buck or slug) should be kept separate on a side saddle or stock carrier. This way there is no question with the performance and option that you have loaded. You won’t shoot a slug unless you have it loaded or swap it as needed. If I am hunting bear, I might load with slugs. Home defense might get Federal Flitecontrol #1 buck. If I am hunting birds… Something also to bear in mind, diferences in husk color will not help differentiate shells in all lighting solutions either.
Staggering rounds only makes the gun less effective and wastes time. If I need deadly force, I need it now! I shouldn’t have to waste time shooting the less effective round or eject it out. I have a Beretta 1301 which is a fast shooting gun, I don’t want to waste time even if I can get that first shot off fast.
This practice also limits the capacity of viable effective shells. Less effective shells are taking up space where effective could be. No matter the shell you are using it is deadly force – so make sure it is appropriate and effective. If you have bird shot or salt loaded, it is still deadly force despite its poor performance on things other than birds. Use what is most appropriate shells to stop the threats you may be facing.