Assume a TD is bound and determined to use accelerated pairings for a four round open swiss with players of rating ranges up to 2000 including many low rated players and some unrateds, if there are 20 players or more. The wisdom of that choice isn’t the question here (though perhaps it should be.
What’s the best way to do the acceleration in this case? How many rounds to you play before you decelerate?
Four rounds for 20 players is a little earlier than I’d want to accelerate (I’d probably want 24+) but if the rating ranges are fairly smooth (such as every 100 points from 100 to 2000), or if the top five players are significantly stronger than the rest, then it makes sense (under a normal Swiss 1-5 would beat 11-15 in round one and 6-10 in round 2 while round three has 1 and 2 beating 3 and 4 with 5 beating somebody else and round four has 1 vs 2 with 5 playing the two 2.5-0.5 or 2-0 and needing only a final round upset win to tie for first or to take clear first if 1&2 draw each other.
Round one is (assuming seed 1 gets White in round one - otherwise swap the colors)
1-6, 7-2, 3-8, 9-4, 5-10
11-16, 17-12, 13-18, 19-14, 15-20
If the higher rated player wins in all cases then round two is
either
4-1, 2-3, 6-5 (if the temporary added point for 6 is higher ranked than the actually scored point for 11 or 12 resulting in four 2-0 players if the higher player wins them all)
8-11, 12-7, 10-13, 14-9, 16-15
20-17, 18-19
or
4-1, 2-3, 12-5 (if the actually scored points are deemed higher than the temporary add, resulting in two 2-0 players if the higher rated player wins them all)
6-11, 8-13, 14-7, 10-15 16-9
20-17, 18-19
Round three and later normal Swiss pairings with no adjustment for acceleration.
Assume round three has 1-2, 5-4, other.
Assume round four has 5-1, other (or 1-5, other if 1&2 drew).
That would leave a single perfect score.