Duomo tickets - do I need a time entry if we're not climbing the dome?

The €16 special is only sold at that office, not online, and appears to just the two museums, not the dome, baptistry, crypt, and belltower. [Museo della Misericordia](Museo della Misericordia) is not in Rick's book and regular entrance fee is €4.

When you click through further to purchase the €18 Cumulative Ticket, you find these timing details:

✤ Valid for 30 days from the date selected for the visit on the calendar at the moment of the purchase
✤ Usable for 72 hours from the first passage
✤ One entry to each site
✤ Direct access without going through the cashier queue
✤ Access will be permitted only for ticket holders
✤ Mandatory booking to access the Dome
✤ The booking for the Brunelleschi's Dome cannot be modified.

IMPORTANT: Any errors on the selection of the date of visit will not be refunded

Ticket contains a barcode readable by the turnstiles at the entrances of the various sites. The use of the tablet is not advised for reading difficulties of the bar code at the entrance.

Tickets cannot be canceled or modified and are not refundable unless the monuments remain closed for the whole period of validity of the ticket.

P.S. By purchasing online, the main benefit aside from a dome reservation is probably just to skip a ticket buying line locally. Ticket windows might have a line and ticket machines there on the spot require a PIN for your credit card.

We bought tickets on the spot, choosing a limited ticket that included Duomo Museum, Baptistry but NO towers (I don't do mornings and I don't do towers without elevators.) Duomo itself is easy -- if there's a line just come back later.