With SegMate, there are two different types of Sequences you can use.

Evergreen Sequences
Evergreen sequences work much like an email autoresponder sequence. A sequence is a series of Bots sent to Subscribers based on the timing of when a Subscriber enters the sequence.

Let's use the following example:
A sequence is set up with 3 "segments". A "segment" represents a Bot message to be sent at a specified number of hours or days after the Subscriber enters the sequence.
Segment #1 is set to send, 1 hour after a user enters the sequence.
Segment #2 is set to send, 12 hours after Segment #1.
Segment #3 is set to send, 18 hours after Segment #2.

So as you can see by the example above, the sequence begins once a Subscribers is entered into the sequence & based on the timing settings of Segment #1. So with Evergreen Sequences it does not matter when the Subscriber is entered into the sequence as all Subscribers entered will follow the timing settings applied in each sequence segment.

Reminder Sequences
Reminder Sequences are based on a particular "End Date". Reminder Sequences work best for an Event, such as a Webinar, as it has a pre-determined date & time.

Let's use the following example:
A Webinar is scheduled for January 8th @ 8pm EST. In our Reminder Sequence we would create a "segment" for each Reminder we want to send.
Segment #1 is set to send 48 hours before the Event date/time. In this case it would be set for January 6th @ 8pm EST.
Segment #2 is set to send 24 hours before the Event date/time. In this case it would be set for January 7th @ 8pm EST.
Segment #3 is set to send 2 hours before the Event date/time. In this case it would be set for January 8th @ 6pm EST.

So as you can see by the example above, the Reminder Sequence sends Bots that lead up to a pre-determined date & time.

Depending on your goal, you can use either type of Sequence to suit your needs.