Do you ever find you get an error, where a workflow/plugin sometimes fails. It could be because it's being called by a chain of workflows and your hitting the maximum depth. The default is 8 for on premise.
Powershell script
A useful poweshell script to increase the the depth of calculations in Dynamics 365
Add-PSSnapin Microsoft.Crm.PowerShell
$setting = Get-CrmSetting WorkflowSettings
$setting.MaxDepth=10
Set-CrmSetting $setting