Rangers manager Mark Warburton thinks Scottish football would benefit from a 16-team top-flight, but his Celtic counterpart is sitting on the fence.
Ronny Deila says expanding the Premiership would bring with it negatives as well as positives.
League restructuring has reared its head again as an agreed three-year period of stability comes to an end.
"The gap between the top of the Championship and Premiership is not the same as down south," said Warburton.
"Up here, the gap is much narrower and you can afford to have a competitive 16-team Premier League.
"I keep being told about the financial climate, but sometimes it's short-term pain for long-term gain.
"Right now, it's not working. I keep being told about problems with the national game, I keep being told that radical measures are needed; well, there might be some short-term pain."
While Deila's reigning Scottish champions again lead the Premiership, city rivals Rangers hope to join them in the top flight next season.
They lead the 10-team Championship ahead of Hibernian and Falkirk, whose chairman, Doug Henderson, and manager, Peter Houston, both recently went public in support of bigger leagues.
Warburton said Houston had spoken "very well, very wisely" about restructuring, with the Rangers manager insisting that teams should only benefit from any changes on "sporting merit".
He said the most obvious drawback of the present system was teams playing one another four times.
"By the end of November, we'd played Livingston three times, Hibs three times," Warburton pointed out.
"We've got to keep it fresh, the quality of product the best it can possibly be.
"Right now, something's not working. That's what I'm being told by all and sundry.
"We either keep on talking about it or do something about it."
Warburton thought that national manager Gordon Strachan would benefit from more young players being given the opportunity to gain experience in an expanded top-tier.
Deila did not feel properly qualified to give an opinion on the matter until he knew in detail what exactly might be proposed.
Asked about the present system, which has 12 teams, the Celtic manager said: "It should be higher quality.
"If you get more teams in, are there going to be more games or fewer games? I haven't seen the plans.
"When you have more teams, it's easier for talents to grow up and to get a chance.
"And you get games spread over the whole country, so everybody gets to see Celtic and other big teams."