I did this more or less as an experiment

The idea of preferring slow speeds is that you contribute to with a small % (say 1%) to each block
worded by your mining pool. If your MiningPool wins that block, you get your 1% of the reward associated
with that block. Otherwise my computational power is lost.
So, if your mining Pool wins say 10blocks/day, after 1 day of work statistically you get (10*Reward_of_each_block)* (1%).
The problem, instead, of renting a lot of computational power for a short time is that I might
contribute 50% just for a couple of blocks, and if those blocks don't win, I'm screwed.
(If the win, instead, I can get much more reward).
Is what I wrote above correct? Sorry I'm a total noob with mining!

Another specific question: what are the 'Round Shares' ? Are they collected over multiple blocks, or reset to zero after each block (won or lost)?