Time for Cullen's men to prove they have learned from their mistakes
In seasons gone by, apart from the end of year performances in the Pro12 and the Champions Cup, the next yardstick to judge where teams stand is the informal inter-provincial rankings.
While the results of these games wouldn't make waves across European or Celtic rugby, the importance at home is two-fold: Irish team status among the players and the high-level derby games that prepare and rejuvenate each team for the next round of European action.
If one was to reflect on what Leinster have achieved so far this season, rarely in the past would you be able to pick out so many positives while disregarding a relative hammering in Thomond Park.
Yes Munster are back valiantly with their 16th man in tow, who speak with their feet these days and why not, when finally all of Munster's top performers are playing well.
Conor Murray, Simon Zebo and Donnacha Ryan are consistently bringing pride and performance back into the red jersey but for Leinster, frankly speaking this fixture doesn't seem to matter any more.
With one loss from four, it would be irresponsible to dismiss our most valued southern brothers, but Leinster went to Thomond Park with an open view of the season, not just one game.
With Leinster opening the scoring early on, it took a while for their youth to feel the real roar of the Thomond crowd but at full-time it felt more of a battle won by Munster more than a war.
It was a match Munster needed to win more than it mattered if Leinster lost. Leinster's greatest legacy left from this season will be their ability to pick and plan teams more than one game ahead and leave the hype to the marketing department and selection to the coaching staff.
Roll on five days later and for the first 40 minutes, Leinster obliterated Ulster, who were shorn of their top players.
Rory O'Loughlin's score will be try of the season and his enthusiasm was matched by Adam Byrne on the right wing. There is no doubt that the players are enjoying themselves but don't enjoy it too much as you'll leave the bonus points behind and it won't be as easy to turn the screw on stronger teams then Ulster.
Leinster's younger players showed inexperience by letting Ulster back into the game but the learning curves have been ascending in the Dublin 4 camp and confidence is evident in their play as they look like peaking at the right time of the season.
So looking to the immediate future, maximum points will be expected against Zebre but with many injured men soon to be available, it gives Leo Cullen an ideal chance to bring back his frontliners and let them prove worthy of selection.
With the new tackle rules in place, expect some hesitancy from both players and the referee. Leinster's penalty count has been creeping up recently and will cost them eventually if it is not addressed.
They need to beat Montpellier at home in the Champions Cup and once that's achieved, Castres could be out of the campaign by the time Leinster travel there on the January 20.
With the abundant squad comes the silly season from March onwards - who will move, who will stay etc.
Already Noel Reid has been asked about his commitment to Leinster and with David Nucifora in the shadows, decisions can be made for players.
The large squad is great for covering injuries but when all players are available, everyone will want to start. It is imperative that this squad is kept happy -and when I say happy, they must also keep winning.
Clarity and consistency in selection will be vital to the players' welfare and Leinster can plan more confidently than most others.
In professional rugby, time moves fast and there is no time like the present as opportunity may not come around again so easily.
The losses away to Montpellier and Munster this season have been addressed and excused. This Leinster side needs to prove that it has learned from both and also from the slip-ups last season.