Points to note while updating a field used in a layout rule.
Layout rules are effective on creating a record manually. However, when a field used in a layout rule is updated through other ways such as workflow update, and APIs, the field update takes precendence over both these rules.
These instances are explained with further examples below:
Layout Rules - Details of the exceptions
You have a layout rule for the Leads module that says,
<<If Lead Source is Tradeshow, make the Emailaddress mandatory.>>
This layout rule will work when you manually create or edit a record in CRM and update the Lead Source to Tradeshow. However if the Lead Source is updated as Tradeshow via the following means, Email address will NOT be made mandatory and as a consequence, the Email address field value will be empty.
|Means of field update in CRM||Field update details|
|Import||Updated on importing new leads or overwriting existing records|
|Workflow rules||Updated as a result of workflow action|
|APIs||Updated via API updateRecords method|
|Mass update||Primary field used in a layout rule will not be available for mass update.|