Can we use FIELDS(ALL) in Batch class START method and is it safe?

I have this validation rule that works when a user follows a linear approach, however, if the user decides to skip the stage listed in the VR, they will bypass this VR and will be able to skip this stage. 

Any idea on how I can improve this VR so that the user doesn't have the ability to skip stages in an opportunity when saving the record? 

This VR prompts the user to enter a value in the Resolution_Type__c picklist when saving the record. However, if a user skips this stage and selects the stage afterwards, named Secondary, the record will save and the Resolution_Type__c picklist will remain blank. 

I am trying to avoid the Resolution_Type__c  picklist from being left blank. 

The additional stages after Ti In Progress are:

Primary__c
Secondary__c
Qualfied__c


 

AND( 
ISPICKVAL( StageName, 'Ti In Progress'),
RecordType.Name="Personal",
ISBLANK(TEXT( Resolution_Type__c))
)

Thank you!

I am using the REGEX function in a workflow rule, but I keep getting an error

Error: Function REGEX may not be used in this type of formula

I checked https://help.salesforce.com/htviewhelpdoc?id=customize_functions_i_z.htm&siteLang=en_US#REGEX (https://help.salesforce.com/htviewhelpdoc?id=customize_functions_i_z.htm&siteLang=en_US#REGEX) and it says that REGEX is available everywhere except formula fields and custom buttons.

Can anyone tell me why this is not working? 
 

RecordType.DeveloperName = 'IT Case' && REGEX(Description, '[A-Z]{3}[0-9]{1}')