Duration of object changes after its moved

I recorded my screen while completing an online form that financial advisors must use when they submit non-financial transactions, like a name change for a customer. I selected step-by-step slides when I was done. I wrote down the start and the end frames of the different video clips on each slide. The unnecessary slides, like clicking to open a drop down list, were deleted while the slide that shows the selection being made was kept. The other slides had their start frame extended to match the start frame of the preceding slide.

For example:

• Slide 1 = 1 to 25
• Slide 2 = 26 to 50
• Slide 3 = 51 to 75

If I delete slide 2 and extend slide 3, then slide 3 = 26 to 75.

Because my slides do not start and stop after 1 s (= 25 frames), end up with fractions of a second (1 frame = 0.04 s).

On one slide, the new start frame is 18 frames earlier than the default values selected by Articulate. In order to help with aligning video clips and mouse movements, I am inserting rectangles in the working area of the canvas. Since 18 frames is 0.72 s, I typed that value in the duration text box of the rectangle. When I moved the shape to the proper location in the stacking order and along the timeline, the value changed to 0.73 s.

I expect that if I type a value, then it should remain that value. Articulate is able to discriminate hundredths of a second, so why does it need to change the value that I typed?

Depending on the number of actions that need to be played during the video clip, I could need 5-6 rectangles to act like guides on the timeline. Since I need greater precision than 0.25 s increments, this is the best solution that I have come up with.

Because the value changed from 0.72 s to 0.73 s, it means that the video starts 0.01 s earlier than I am expecting. That could affect my animations, because I am basing everything off of the start frame of the video clip.

Can someone explain why a manually typed value is changed by Articulate when it is moved in the stacking order and along the timeline to align with other objects?