If you have 8 or less specialization buildings, there will always be a task on all of them. If you have more than 8, then only 8 tasks will be available at any given time. That's why it's best to only have 3 token specialization buildings, otherwise the tasks could end up stuck on those 1-2 token buildings, and those will make you take longer to reach your goal.
Gambling only has 1 & 2 token buildings. I have 6 x 2 tokens (and 1 x 1 token), and managed to get gold project both times, it wasn't as hard as I was expecting, but it does get harder from 100-160 points. Expect it to take 50% longer, and 50% more expensive. I do them because they offer different designs, so far I have "Tower of Poker" and "Tower of Big Stakes", and there's at least 1 more called "Epic Club Tower". There's usually a varied colour of each building depending on bronze/silver/gold project.
Don't forget that you can hit the 'refresh' button on the epic project building to get issued another specialization, you don't have to do the specialization it initially gives you.