Time, Tempo, and Meter : Tempo : Tempo and Automation Drift (With Sample-Based Clips on Tick-Based Tracks Only) : Minimizing Automation Drift
 
Minimizing Automation Drift
In general, automation drift is more pronounced with larger sample-based audio clips. By creating many small clips, the effects of automation drift can be minimized, because the start points of each subsequent clip changes as the tempo changes. When tempo is decreased, automation expands. When tempo is increased, automation contracts.
*You can also separate clips at transients or based on the current grid resolution. For more information, see “Separate Commands” on page 326.