Tasmania wicketkeeper Matthew Wade is not buying in to the theory that a couple of big scores in the JLT Sheffield Shield warrants a Test call-up.

While Australia coach Justin Langer has declared batting spots in the Test top six are up for grabs as his side continues to suffer from consistent collapses, Wade – himself a contender in rich form – believes it will take "something extraordinary" for a batter to break into the Test XI.

"If guys are doing alright at Test level you have to do something extraordinary to try and overtake those players that are already in the team," Wade said today.

"If the players in the team are already doing reasonably well and there's no-one really setting the world alight then I don't feel like anyone should leapfrog a current player that's already in the squad."

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Five Shield rounds were scheduled before the first Domain Test of the summer, against India at Adelaide Oval from December 6, to give Test incumbents and aspirants plenty of opportunities to either mount a case for selection or spend time in the middle before national duties.

After two rounds, seven batters have scored a century, five have amassed more than 200 runs and four average more than 100.

Leading the way is Victoria's Marcus Harris, who pummeled NSW for 250no at the MCG last week, while Wade has scored a half-century in each of his four knocks to start the summer.

Full highlights as Harris hammers 250 not out

The numbers for Australia's top six in the UAE make for less encouraging reading.

Aaron Finch scored five runs in four T20 innings after his impressive maiden Test campaign; Usman Khawaja is recovering from knee surgery, Mitchell Marsh lost his ODI spot and rookies Marnus Labuschagne and Travis Head failed to fire in the Shield return.

The only player who thrived in his Shield comeback was Shaun Marsh, perhaps the batter under the most scrutiny, who was sublime in putting together scores of 80 and 98 against Tasmania.

Marsh tames Tigers but falls for 98

However, one match does not make a season.

Wade, who admits his days as a Test gloveman have expired, says the focus on early-round Shield performances is overblown annually but warns against picking players with a few solid performances under their belt.

Instead, he reasons Test players have been chosen for consistent performances over an extended period, and that sustained form should be what counts.

"There's a lot of talk about the first couple of Shield games leading into the Test series," Wade said.

"Yes, there's positions available but four hits shouldn't really dictate your opinion on a player.

"Personally, I think there is a bit of a beat-up about it.

"There's a certain amount of players that are a chance to get picked but people who score a couple of fifties or go alright in the first two Shield games aren't just going to be straight in to the Test team.

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"The guys who have been picked in the Test team are there for a reason – they've done well for a period of time.

"Unless you're Marcus Harris getting 250 it's going to be hard to leapfrog those players.

"That's how it's always been.

"Unless you can do it over a long period of time, that's how you get picked for Australia.

"Matthew Renshaw (who made three and zero in his first Shield game back), a lot of pressure on him at the moment, but he's been a good player for a long period of time.

"It shouldn't be about four innings, in my opinion."