A late decision to announce a double-header at the Reid Park Street Circuit subsequently resulted in a tyre shortage.
As a result, teams were required to pre-mark 12 used tyres from last weekend's Townsville 500 to use at the Townsville SuperSprint alongside 20 new ‘event marked' tyres.
Typically, of the 32 tyres each car is allotted at SuperSprint events, only four of those are pre-marked with the remaining tyre bank new.
For Mostert, who spent much of the Townsville 500 struggling to get up to speed, the tyre allocation was of no help in his efforts to better understand his Holden ZB Commodore.
“A lot of changes in the session, obviously after last weekend we're still soul searching a little bit,” said the Mobil 1 Appliances Online Racing driver.
“That's been the worst session all year, and it's not from our team performance. I've never been motor racing when we don't have tyres.
“It's been very tricky coming from last weekend to this weekend and we're just running around on [old] tyres so it makes it hard for us to make solid gains when we're just questioning the tyre the whole time.”
Only a handful of drivers went out on a fresh set of soft tyres in Practice 1, namely timesheet topper Scott Pye of DeWalt Racing.
The Team 18 driver set the pace on a 1:12.9331s while Mostert was only 13th fastest with a 1:13.5718s, some six tenths off the top time.
“It's going to be a tough qualifying for us,” said Mostert.
“I definitely feel a little bit more optimistic this weekend than we did last weekend. The boys are working extremely hard throughout the week to understand what the car needs.
“I think we were probably a bit stronger at the start of the session than we were at the end of the session there. We'll dig back into the report and go from there.
“Motor racing, no brakes and no tyres, how fun?”
Qualifying for Race 17 at the Townsville SuperSprint gets underway at 13:45 AEST.