I feel like they are growing way too big, and they are not aware of the peak times that they are having. Reality is that while that's good for a website because every casino will want to have more and more people that gamble on their platform, you also have to end up with a situation where both maintenance and server load could be handled by the development team as well.
If you end up getting a small team and push them relentlessly to make everything work, even with extra hours you will not get what you need, when you are this big then you will need a whole team of people who could do this. Stake obviously does not have enough developers, no matter how great the developers they have right now, if their number is not enough, they won't be able to reach to every single issue.
I think this kind of maintenance is still quite reasonable and any casino does the same thing. Stake.com carries out maintenance for a fairly short duration, but regarding developers so far there is no open data regarding the number available or do you have a source regarding the number of developers from each casino?
The maintenance process is a positive thing to maintain player comfort in the future. Here Stake.com is actually routine because they know how many visitors come at the weekend. I used to play at a well known casino on this forum, but the login process was very slow, I even had to refresh several times just to be able to enter. You also need to remember that there are also casinos that are difficult to access and require a VPN so the loading process is 2x slower, requires confirmation, sometimes certain game providers are not available, even though the visitors are not dense, you will definitely be annoyed if you experience a lag in the middle of the game.