When will their batteries run out?
That is a question Sharks head coach Sean Everitt must be mulling over regarding his ever-present lock pairing after six matches in Super Rugby 2020: Ruben van Heerden and Hyron Andrews.
Just as importantly, Everitt will be praying it isn’t this Saturday - assuming both are duly installed to the starting XV once again - when coastal arch-rivals the Stormers visit Kings Park (15:05 kick-off) for a key derby.
The duo have started every match in Super Rugby this season: a yeoman contribution to what was always going to be a difficult workload for the entire team, as their roster is split into two long shifts of eight matches each, with just one “real” bye in between, on the weekend of March 27/28.
Their other bye is a relatively useless one from a round-robin point of view as it comes on the final weekend of ordinary season for them, even if it may present some freshening possibilities ahead of the knockouts ... on the assumption the KwaZulu-Natalians, current conference and overall log-leaders, make it that far.
The pack, for fairly obvious reasons, tends to be the area where rugby teams more acutely feel the need to rotate personnel from time to time, and Everitt has done so, to at least some degree, in most positions up front.
But the second row is a glaring exception at this point.
It was always suspected that lock would be a department where depth of proven resources at this level could prove problematic for the Sharks in 2020.
Between seasons, they have seen the departure of two experienced players in that slot, Ruan Botha (to Kubota Spears and London Irish) and Gideon Koegelenberg to tournament rivals the Rebels.
It is probably safe to say the 28-year-old Botha - a former SA under-20 star who would almost certainly have won Test caps by now had it not been for South Africa’s extraordinary reservoir at lock - is especially missed, although Koegelenberg, like him, is a 120kg-plus specimen who offers significant grunt to an engine room.
In their absence, specialist front lock Van Heerden and rangy No 5 athlete Andrews have carried a heavy load as front-liners this season, although Boksburg-born former Waratahs player Le Roux Roets (one of the heftiest second-rowers in the competition at around 138kg) has been a regular infusion off the bench during the second half of matches over the first few weeks for the Sharks.
That pecking order may well stay intact for Saturday’s challenge from the respected Stormers forward unit, even if red lights will just be starting to flash over fatigue to the first-choice pair.
By contrast, Stormers mastermind John Dobson has been in a position to mix up his lock combinations a tad more liberally during the campaign to this point, and there is the additional advantage - at least in some respects - that his charges collectively enter the Durban showdown off a rest weekend.
The Capetonians began the campaign with Salmaan Moerat and Chris van Zyl as their starting alliance - a situation that encompassed successive victories over the Hurricanes, Bulls and Lions.
But then another welcome development came into play: the return to action from pre-season injury of lanky JD Schickerling, the 24-year-old from Calvinia who has previously represented SA ‘A’ and is known to remain on the radar of Springbok director of rugby Rassie Erasmus (so probably also new head coach Jacques Nienaber) despite the abundance of choices available to the national cause from planet-wide.
It meant that Dobson was able to infuse Schickerling in round four against the Jaguares (Van Zyl moved down to the bench), and then he put him into a combination with Van Zyl (this time Moerat shifting to the “splinters”) in the galling, heavy first defeat of the season against the Blues at Newlands.
Round about now, Schickerling should be shedding the cobwebs of his earlier inactivity at a healthy rate, and hungry to hit the ground running in the Shark Tank.
By contrast, the hosts’ premier pair of Van Heerden and Andrews will be on the proverbial reserve tank of energy levels, with two matches still to go (the other against the Chiefs in Durban a week onward) before the squad take a collective breather from the competition.
*Andrews and the now departed Botha were the starting lock pairing for the Sharks when they lost the corresponding Kings Park fixture to the Stormers 16-11 last season, while for the winners Schickerling was partnered by Bok meanie Eben Etzebeth - in his final year on the WP Rugby salaried books before his big move to Toulon.
*Follow our chief writer on Twitter: @RobHouwing