Sweetening a roll is an idea from the Civil War or earlier in history.
If a new drummer was put into your unit or you were camped with another units drummers, they would test them by asking them to play a tune. However, the open left hand roll attack was delayed in time to make the roll faster - sometimes much faster - to see what kind of chops there were.
Any drummer from the Sons of Liberty or St Francis Parochial School taught this delayed attack roll.
The CD's of 1951 and 1952 drum and bugle corps have this phrasing prevalent in the shows due to the heavy fife and drum influence. My instructor taught a Seven Stroke Roll into Seven Singles with a delay on the singles. It is very physical and technically difficult. Try it for a minute or two using the fife and drum predatory motion of lifting BOTH sticks for the roll attack and keeping the singles loud and strong.
These days, DJ's have a button that allows them to play "rolls" but dont have the ability to phrase musically. Using a high pitched and tight hi-hat metallic sound, they use Four Stroke Rolls without a release and Nines much of the time. The DJs haven't figured out how to sweeten the rolls or apply dotted figures from Swiss and Pipe Band genres. They seem stuck in the 16th-32nd note base with a weird mechanical sound that doesn't change and has no accents.
Condensing an attack roll into the 40th note base or snapping in a fast left hand 7 catches the ear of most audiences. Their eyes catch the speed and arm movement. Sweetening is an additional contrast. Instead of playing Ruff-Rat-Drag figures open, you can close the grace notes down far past "correct interpretation" to attract attention. It is a distinct sound, especially using a hi-hat the pierces through the melodic line.
(to "El Divino 5" Ibiza Island Progressive House)
7 Stroke Rolls Reverse Tap 6 40th Note Base Decrescendo Hand to Hand Reverse Ruffs Condensed Hertas
Sweetened One Handed Single Drags
Sweetened Open Ruffs Hand To Hand
7 Stroke Roll Into Sweetened 7 Singles (The favorite coordination exercise of Sons of Liberty Players)
(to "Empty Spaces" Ibiza Island Progressive House Tune)
Swiss Trips Sweetened Reverse Tap 6 40th Base Decresendo Rolls
Double Paradidle 24th Note Mill 24thFlam Triplets 24th Mill Stroke Reverse 5 stroke Roll Reverse hand to hand Ruffs
Double Flam Trips Flam Drags 16th Flams 16th Flams Accented Triplets Four Flam Paradiddle 22nd Note Padaflas w 24th Note Triplets Single Stroke Ruffs Hand To Hand
Sweetened 7s Sweetened Drags & Ruffs 32nd Paradiddles
Sweetened 40th Base Tap 6 Stroke Rolls
Towel Sweetening Practice
Endurance and strength building with sweetened rolls and complex flams
(to "Little White Roses" an Ibiza dance tune from Paris)