Pattern

# this file runs every tick (or more slowly using a ticker)

# start
execute if score TL$exampletimeline DatapackManager matches 0.. run scoreboard players add TL$exampletimeline DatapackManager 1

# timeline
execute if score TL$exampletimeline DatapackManager matches <time_in_ticks> run <command>

# end
execute if score TL$exampletimeline DatapackManager matches <end_of_timeline>.. run scoreboard players reset TL$exampletimeline DatapackManager

Benefits

• Works with any ticker to create a timeline of events
• Test if the timeline is running with execute if score TL$exampletimeline DatapackManager matches 0..
  • It uses the quirk that scoreboard reset is not a number and thus will not be flagged by 0..
  • Alternatively, select a specific range of the timeline execute if score TL$exampletimeline DatapackManager matches 100..350
• Laggier but more readable alternative to having hundreds of files scheduled in a linear fashion
• Works on versions without the /schedule function, 1.13

Example use cases

# this file runs every tick (or more slowly using a ticker)

# start
execute if score TL$exampletimeline DatapackManager matches 0.. run scoreboard players add TL$exampletimeline DatapackManager 1

# timeline
execute if score TL$exampletimeline DatapackManager matches 20 run say 3..
execute if score TL$exampletimeline DatapackManager matches 40 run say 2..
execute if score TL$exampletimeline DatapackManager matches 60 run say 1..
execute if score TL$exampletimeline DatapackManager matches 80 run say Go!

# end
execute if score TL$exampletimeline DatapackManager matches 80.. run scoreboard players reset TL$exampletimeline DatapackManager

# start timeline
scoreboard players set TL$exampletimeline DatapackManager 0