The economist in me is laughing right now, but also very sad at the lack of stats knowledge in our player base.
Yes, if you do the same 1% chance thing over and over, your chance of eventually getting it will be higher.
And, if Dave's code is structured to relatively disadvantage large fleets (giving them increased chances of conquest but at a diminishing marginal rate with each additional ship), then, yes, the optimal strategy is to send lots of small fleets rather than a few big ones.
That is, of course, assuming a one-round game. Dave has clearly incorporated a code that damages planets and ups the odds of conquest. This feature might scale more linearly, or even convexly, making big fleets better and with an increasing marginal destructive efficiency. I don't know.
In sum, very simply, spamming small fleets is better than one big fleet, under the assumptions:
1. There are diminishing marginal returns (measured as % chance of captured added per ship) on each additional ship
2. There are diminishing marginal returns (measured as society level/population decreased per round) on each addition ship
3. There is no inhibiting code which creates diminishing marginal returns as the number of planetary capture attempts in one turn increases
Under those assumptions, spamming is better. A significant enough violation of any one of them, especially assumption 3, could put everything back in favor of big fleets. Big fleets also, of course, have the benefit of being able to kill defending fleets more effectively.