It sounds like there are a couple things you are misunderstanding about how the Maestro and Maestro Control Center work.
The “duration” of a frame is not related to the speed of a servo or how long it takes to move from one position to another. It is simply how long you want the sequence to delay before calling the next frame.
The Maestro Control Center’s sequencer does not save speed or acceleration settings between frames. It essentially just saves a snapshot of the target position for each channel when a frame is saved. When the sequence is played back, it will use whatever speed and acceleration the servo channels are currently configured with. You can set the default speed and acceleration of each channel in the “Channel Settings” tab of the Maestro Control Center, but if you need the speed or acceleration of a specific channel to change throughout the sequence, you will need to copy the sequence to your script and manually add the
ACCELERATION commands where desired. (Please note that all subsequent movements on the specified channel will use those settings until the Maestro is reset or you change them again).
For your original question about having a servo move 180-degrees slowly throughout your sequence, instead of having a frame specifically for that servo, you should set the channel’s speed to 1 and have that channel set to the desired final position the whole time (i.e. in all of your other frames). Since that servo’s target isn’t changing, you can just leave it set to the desired final position in each frame and the Maestro will continue driving it toward that target at the specified speed.
On the Mini Maestro, with the default period setting (20ms), the speed is in units of 0.25 μs / 10 ms, so it will change by 25μs per second. This means to get from 1000μs to 2000μs will take 40 seconds. You might be using a slightly wider pulse width range to get 180-degrees from your servo, but if you need the servo to move even slower than that, you could try increasing the period slightly. Please note that the period controls several aspects of the Maestro servo channels (such as the frequency and allowable pulse width range), so you should be careful when changing it. You can find more information about the speed and period settings in the “Channel Settings” section of the Maestro user’s guide.
By the way, since you are new to the Maestro, I recommend taking it slow at first. For example, maybe try making some smaller sequences that only use a few channels. Then, you can use that to practice adding speed changes in a script and get comfortable with that before trying to do a full 24-servo sequence.