Voyager referenced or included TOS and TNG characters in at least eight episodes of season 3.

• “Flashback” was the big Sulu/Rand/Kang 30th anniversary tribute
• "Death Wish" had Q and Riker
• In “Alliances” Tuvok talks about Spock and recaps the events of Undiscovered Country
• McCoy was mentioned in "Lifesigns"
• Data was mentioned in "Prototype"
• Sulu was mentioned in "Tattoo"
• Picard and Moriarty were mentioned in "Alter Ego"
• Picard was mentioned again in “Scorpion”

That’s basically a third of the season, assuming I didn’t forget any. And that’s not even counting things like the mention of Wolf 359 in “Unity” or the koon-ut-kal-if-fee in “Blood Fever”.

And that’s from the show that went out of their way to make it hard to use existing concepts.