How to split video in small clip?
General speaking, you can not split already encoded video into some chunks with arbitrary length without re-encoding.

The simplest way to make a cut is to get content between IDR frames. You could split your video sequence into segments that contain arbitrary number of GOPs (sequence of frames starting with IDR frame with length to next IDR) each. In this case, you could just copy the content without re-encoding.

So, you goal is to find out appropriate IDR frames, that satisfy you clip duration, and make a cut with copy. You lucky ffmpeg use -noaccurate_seek for copy. You could point start position by -ss and duration with -to near IDR.

You could face some challenges here:


original video sequence has a variable GOP length - clip duration
won't be the same; 
original video sequence has an infinite GOP
length (only first frame is IDR) - impossible to split it without re-encoding;


In your example you should move -ss and -to options before -i, because you want to seek start position in the input video.