In the three seasons since the introduction of the play-offs, the side that has finished top of the table has gone on to win the title just once, Munster in 2010/11.
On the other two occasions Leinster have not been able to capitalise on the home advantage granted to them for finishing top of the pile, losing out twice to the Ospreys in finals played at the RDS.
This season's top seeds Ulster spent 15 of the 22 rounds leading the table, and having slipped down to third during March, bounced back up to lead for the final three rounds.
Their opponents, the Scarlets, despite losing to Benetton Treviso last time out, were still able to secure the last semi-final spot as their nearest rivals, the Ospreys, also lost in their final game against Leinster in Dublin.
It is appropriate that the other two play-off participants, Leinster and Glasgow Warriors, face each other as they had both been battling for home advantage over the second half of the season, each of them taking over the top spot in turn when Ulster faced a dip in form.
In the end Leinster took advantage of a better run-in and held onto the second place they had claimed three rounds out.
And so the scene is set, the last four teams know just 80 minutes stands between them and a place in the RaboDirect PRO12 final on Saturday, May 25 (kick-off 4.45pm).
RABODIRECT PRO12 - SEMI-FINALS:
Friday, May 10 -
ULSTER (1st) v Scarlets (4th), Ravenhill, 7.45pm (live BBC 2 Northern Ireland/RTÉ Two/S4C)
Saturday, May 11 -
LEINSTER (2nd) v Glasgow Warriors (3rd), the RDS, 7.35pm (live TG4/BBC ALBA)