Having been on the examiner side, often as an external you're a bit vexed by the individual "Uni rules vs Uni culture". Logic somewhat dictates you give a good candidate as much time as possible to do the corrections, because - why not? Culture sometimes dictates it's seen 'worse' as having 6-month corrections instead of 3-month, because it somehow implies the work was worse and therefore needs more time.
It's probably the case, as I've seen happen, the chair just asked the examiners along the lines of 'should we give them 3 months, or 6?'. The examiners responded just by giving you more time, because it makes life easier for you, rather than as a judgment of quality. It might have been the case as well, as I've become more sensitive to as an examiner, that they asked you 'what next', and if you said you have a new role, etc., with all the stresses that come with that, it makes (some) examiners inclined to give more time than if someone will purely do nothing but work on corrections.
In all cases, I'd consider the correction duration as a limit, not a target, and because of the above, if you feel you can comfortably do them in 2 months, I wouldn't hesitate to ask your supervisor for feedback then if they're happy go ahead and submit ahead of time.