Can you make the slider work continuously? For example, can you change the value of a slider at a time interval?

You can animate a slider so that it runs its range automatically over a series of frames. Simply right click on a slider and select Animate.

To make a slider a timeline, hook the slider output into multiple functions. Then as you animate the slider, all the reliant functions will change over time.

Sliders normally only respond to manual input, although, there is a Timer object which can be set up to fire once a second. How you handle these timer events it is up to you. Note, it often does involve a fair amount of scripting.