The AP Poll has existed for 85 years. Maybe it would take forever to see how every school did every year to measure all their ten year stretches. But going by your definition of consistency, finishing in the top-25 60% of the time, only five schools have done that. Only 10 schools have finished in the AP top 25 50% of the time.
Teams outside of that 10 include LSU, Auburn, Georgia, Clemson, Florida. Some of them better recently rather than in years past. Some of the ones in the top 10 were better in years past than they are recently. USC, Texas, Nebraska, Tennessee.
Coaching matters a lot. If James Franklin took over for Fridge, who knows what MD looks like the last decade. Probably a lot better. Maryland has its flaws, but Franklin put together solid teams, selling kids on playing for child molester university. Was there a tougher sell in college sports?
Nebraska has made some bad coaching hires (which I don't understand why Frost sucks so bad given his background) but they haven't finished a season ranked since 2013. I think you can fall out of consistency easier than it takes to stay consistent. If Alabama hires the wrong coach after Saban, they might go the way the of Nebraska. They were unranked 8 out of 11 years before Saban. 12 years if you count Saban's first season there. Florida State, Texas, powerhouse schools that can't find decent coaches recently.
It goes the other way. Clemson had some success in the early 80s. Average up until Dabo Swinney comes in and they go to an elite program. Nat'l titles, 11 of his 12 seasons finishing ranked.
It's not impossible for Maryland to one day find that right combination.
Only 5 schools have had 10 year stretches of consistently being in the top 25? Because that's what I was talking about, not the entire history of the program.