IMO, you should create channels for each campaign-sub-campaign type (e.g., email-nurture, email-multi send, etc.) as most have separate statuses, and your MOPs team would probably be creating programs for these campaign-sub-campaign's down the road. Having campaign-sub-campaign created as channels with progression steps for each would allow you to create, track and report on the programs for each campaign-sub-campaign type. Tag types cannot be used to manage the campaign progressions in the campaign SL/flow unlike channels, fyr! If it suits your MOPs team from a reporting/tracking perspective, you can also condense multiple campaign-sub-campaigns in to a single channel where there are same progression steps e.g., create a single channel for web-form with 'viewed form' and 'submitted form' status values.
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