How do a place multiple markers automatically?

1. Change the timeline from timecode to frames by Cmnd/Ctrl-click the Timecode in the upper left corner of the timeline
2. Add a null
3. Press Alt/Option + s to set a keyframe for Sacle (or any other property using the keyboard shortcut)
4. Type 34 in the Timeline Frames property to move the CTI to 34 frames
5. With the null selected press Alt/Option + ] to set an out point for the null layer
6. Duplicate the null as many times as needed for the number of markers you need
7. Select all null layers, right click and use the Keyframe Assistant to Sequence layers with no overlap
8. Select the layer that you want to add markers to
9. Move the CTI back to the first frame if you want the markers to start there
10. Press Control + 8 to set a marker on the selected layer or don't select any layer to add a timeline marker
11. Press k to jump to the next visible keyframe then Control + 8 again
12. Repeat until you have all the markers then delete the null layers

Unless you want to write a script that's the most automated way I can think of for creating a set of markers distributed 34 frames apart.

What are you trying to accomplish? Maybe there is a more efficient workflow.