arc_74, I agree with ibeweldingsum on the solution. If your keyhole is getting too large you can reduce the amps and or reduce the gap and or increase the land. Another tip is to tilt the rod angle down(increase angle) to reduce the penetration. This can be done while welding to fine tune the bead instead of stopping to change the amps. Also if you need to increase the keyhole you can tilt the rod angle up towards 90 degrees and you will enlarge the keyhole and get more penetration if all other variables remain the same. i.e. depth of rod, whip technique etc.
If you are rusty or not too experienced w/6010 you may consider 3/32" rods for the root and reduce your gap and land slightly. Smaller rod will be easier to control.
The length of the whipping stroke should be approximately 1 1/2 times the electrode diameter or less. The rod should pause at the bottom of the keyhole long enough to deposit metal and raised up enough to keep keyhole size consistent and allow the root time to cool. Pausing at the top of the stroke will allow more cooling but will possibly enlarge keyhole so be careful.
Asking how fast to whip is sort of like asking how do you weave. Every welder has their own style that they use. I would say that a complete cycle for me would be one second. But I change while welding if I need to. Gap widens, closes, keyhole gets too big, small, etc.
I think 60/40 ratio would be close. Pause at bottom 60% and raise 40% Adjust while welding to maintain penetration and keyhole.
Of course all of this requires the correct amperage. If you are fighting the keyhole cut your amps down. It's easy if things go well but it's a lot to digest when it's falling to pieces in a test booth.
If you can practice before the test to get a couple of good roots in that would help. If not just try to relax but have in your mind what to do IF this or that happens. After the root, keep it clean. Remove all slag and porosity if you have any.
Hope this helps and doesn't confuse as I sometimes ramble on incoherently for hours...
Best of luck on your test.