Testting and Analyzing Hollandish System
The Hollandish system is another interesting and popular negative progression roulette betting strategy. A lot of roulette players adopt this strategy because it is so simple to understand and use. Like the Fibonacci system, the Hollandish system is meant to be used on outside bets such as Red/Black, Odd/Even, and High/Low. However, unlike the Fibonacci system, which requires bettors to raise their stakes following a loss, the Hollandish system requires players to place three bets before they alter bet sizes.
How Does the Hollandash System Work?
Let’s start by taking a look at the stake sequence using a starting wager amount of $1:
1, 3, 5, 7, 9, 11 etc...
The basic formula for a series of progressions is as follows: a0; a0+a0*2 ; a1+a0*2; a2+a0*2; …; a(n1)+a0*2. Where “a0” is the initial base bet
As you can see, we are essentially increasing our bets by 2 units. If we were to instead have a $2 base unit, the progression would go like this:
2, 6, 10, 14, 18, 22 etc…
The idea is quite simple. We wager the same amount for three spins. If those three spins result in a net loss, then we increase our stake amount to the next level of the sequence. If those three spins produce a profit, then we go back to the beginning of the sequence. Let’s illustrate by looking at the following scenario and a $1 base bet:

Spins 13
We lose two rounds and win one giving us a net loss for the three spins. We increase the stake amount to $3 for the next three spins.

Spins 46
This time, we win two of the three rounds for a net gain. Sticking with the Hollandish system, we roll our stake amount back to $1 for the next three spins.

Spins 79
We go one for three for a net loss. We move up once again to $3 bets for the next three spins.

Spins 1012
We win just one of three, incurring another loss. Time to raise the stakes to $5 for the next three spins.

Spins 1315
We win all three. Our wager amount goes back to $1 for the next three spins.
As you can see, we wagered $1 for each of our first three spins. Because we took a net loss on those spins, we upped our wager amount to $3 for the next three spins. As luck would have it, we made a profit on those $3 spins allowing us to go back to the $1 level. After going one for three on the next round, our stake amount again goes up to $3. When we finally got positive results at the $5 level, we lowered our stake amount back to the original $1.
Putting the Hollandish System to the Test
To identify the strategy's effectiveness, you need to see how it works in the long term. We used a random number generator in Google Sheets and JavaScript as a programming language to implement the progression of the algorithm. For a broader understanding, let's take three imaginary players playing independently using the Hollandish system. Each player has a $1000 bankroll, and they will each play 501 rounds. We chose 501 because it is a multiple of 3.
The first player will play with a base bet of $1, the second with $2, and the third with $3. For each player, we will draw up the course and flow of the game using a graph. We set the first player loose at the table and got the following result:
The maximum bet amount reached was $17, and it came during the 385th round. The player ended the game with a bankroll of $1021 for a total gain of $21. We can also see how the value of the bet changed during the game.
We then unleashed the second player with a base stake of $2:
This player ended the game with a bankroll of $994, which equates to a negligible $6 loss. In general, it can be seen that the bankroll chart has become more dynamic compared to the first player due to the higher value of the initial bet.
Let's see how the third player with the $3 base bet made out. His progressions were 3  9  15  21  27  33  39  etc…
This player was more fortunate. By the end of the game, his bankroll had risen to $1327 for a net gain of $327. The maximum bet was just $45.
In general, according to the three players' results, the graphs are somewhat reminiscent of steps. In some areas, it may seem that the progression is positive. However, at specific points, the bankroll sagged when the bet amount was increased.
On the whole, the Hollandish system’s progression is negative. It's not too noticeable with the first player, but it’s quite evident with the second player. For the third player, it may not be very noticeable since there were no significant stake increases between the 100th and 400th move.
The Pitfalls of the Hollandish System
Based on the results of our experiment, we can see that there are no significant risks of a complete drawdown of the bankroll. The risks of going beyond the limits of the table are minimal. There is also little risk of going beyond the starting bankroll. However, our players had $1000 each to play with. If they only had $100, then the possibility of bankroll depletion is very real, especially with a base bet of $3 or more.
Winning back losses under the Hollandish system can be a lengthy affair. It’s also possible that attempting to win back losses could end in failure leading you to incur even heavier losses. Like any progressive system, this strategy can take a long time to yield positive results.
Conclusion
We tested the Hollandish roulette system on three players with base bets of $1, $2, and $3, respectively. As can be seen from the results obtained, the larger the value of the base bet, the more volatile the game and the bankroll become. So, if you start with a base bet of $1, the progression is not very noticeable, even over 500 rounds. The peaks and valleys are relatively small. In terms of practicality, it is better to take a base bet of $2 or more.
Due to the moderate rate of progression, there is no sharp drawdown of the bankroll. Still, winning back lost funds takes a long time. If there is a significant increase in the bet, then there is a high probability of sinking even further into the red without recovering the loss.
In general, the progression has a negative trend, although we see upward growth in some "stepped" time segments. You can expect to earn a small profit, take a small loss, or finish near even. This is because evenmoney bets have low volatility. Therefore, it would be logical to stop at a particular moment when you are already in the black.
Using this system or taking a pass is up to you. The Hollandish system can bring you moderate success if you initially have at least $200 in your bankroll, along with a lot of patience.