There are two main aspects to consider with roulette progressions :

1. Using progressions with roulette is very risky and dangerous if you do not use them right, because they might work well for a   
    given period of time and then, when an unexpected losingrun occurs, absorb all the winnings accumulated during days or weeks 
    of hard work.

2. Not using progressions make it much more difficult to win consistently at roulette.

    So, what needs to be explained is :

    How to use progressions right ? 


A.  Casinos offer a certain range of possibilities to vary your bets, depending on the chance you are betting on.
      If for example you chose a table with a 1.- euro minimum bet, in most online casinosyou may bet between 1.- and 50.- euros on a   
      single number. 

This means that : 

IF you are  o f f e r e d  the possibility to place as low as 1.- euro and as much as 50.- euros on a single number and you do not take advantage of that, you are increasing the advantage that the casino has over you.

In other terms : 

If you are  n o t  able to use the entire range of possible bets on a given chance because of a lack of money -  what is the case of 99% of the players - then you should :

- either not expect to win at roulette consistently

- or wait until you  have  the money to use the entire range of possible bets

  ( and this should not be money that you need for other things !!! )

Either you progress seriously, betting up to the table maximum, or not at all.

B. The global result of a roulette system using a progression is always better if you split the progression line into several parts.

Example : your betting system consists in betting a dozen if that dozen has not shown for 9 spins in a row. 
                ( on average, this happens every 34th spin ; Roulette Probabilities Calculator , formula 8 )

If the maximum bet allowed on a dozen is 1000 units, you could apply a progression line comprising 17 steps and win at each step of the progression :

1-1-2-3-4-6-9-14-21-31-47-70-105-158-237-355-533

But : it must NOT happen that a dozen doesn't show for more than 26 spins in a row ; otherwise you are going to lose 1597 units.

This doesn't happen often, but it still happens too often to let you win in the long run , whereas if you split your progression line in several parts, it happens less often, and your chances to win in the long run change dramatically !!!

Referring to the example above, this would mean that you should start betting on a dozen if that dozen hasn't shown for 9 spins in a row, using the progression pointed out above, but only 4 times ( first part of the progression: first bet = 1unit;  second bet = 1 unit again; third bet = 2 units and fourth bet = 3 units  ).

If your dozen doesn't hit, you have to wait again until a dozen doesn't show for 9 spins in a row before you bet that dozen 4 times, using the next four steps in your progression line ( second part of the progression : first bet = 4 units;  second bet = 6 units; third bet = 9 units and fourth bet = 14 units ).

If your dozen doesn't hit, you wait again until a dozen doesn't show for 9 spins in a row and bet that dozen 4 times, using the next four steps in your progression line ( third part of the progression : first bet = 21 units; second bet = 31 units; third bet = 47 units and fourth bet = 70 units ).

Finally, if your dozen doesn't hit, you wait one more time until a dozen does not hit for 9 spins in a row and bet that dozen 5 times, using the last five steps in your progression line ( fourth part of the progression : first bet = 105 units ; second bet = 158 units ; third bet = 237 units ; fourth bet = 355 units and last bet = 533 units )

THIS IS THE RIGHT WAY TO PROGRESS WITH ROULETTE !!!

BUT STILL THIS ISN'T ALL

If for example, you apply the system explained above ( waiting for a losingrun of 9 spins in a row on a dozen ), you need patience.
Unfortunately, most of the roulette players don't have enough patience, at least not in the long run. 
Further more, it would be even better to wait for a longer losingrun ( 10,11,12,13 or even 14 spins in a row ) before you start betting, expecting the interruption of the losingrun to occur very soon of course. And this needs even more patience.

The solution to this problem is to track as much roulette chances and losingruns as possible, and to predefine the lengths of the losingruns in a way, that there will be JUST enough losingruns to occur , so you don't lose patience.

The more roulette chances and losingruns you are tracking, the longer the predefined length of those losingruns can be.

Don't think that the online casinos are not aware of the fact that people are using computers during active play to improve there chances to win, but the number of people who do that is certainly still very, very low. Most people are not ready to make the effort to study roulette seriously and to take advantage of the possibilities they are offered by modern computer technology. They want to win quickly, make 1000.- dollars out of 50.- and have fun at the same time. They don't consider "playing" roulette seriously.

Therefore, the casinos have nothing to fear and absolutely no reason to cheat on there customers. The many players who lose in the long run bring enough profit, so the casinos don't care about the few, serious players who cash in there winnings at the end of the month. 
But still, you must not exagerate. If your winnings get too high, a casino always has the legal right to stop you.
And also, even if the casinos basically have no reason to cheat on you because of the reasons pointed out above, some do.
Not all the online casinos are trustful.