I've been blocked only once, but it was horribly frustrating : a Fairchild metro can fly 6 short routes a day. So, as usually, I opened 6 additional tabs in opera, each one for a route, and this time, I had 6 different destinations(yeah, serving 602 airports needs quite work - but that's normal). I check everything is OK, all routes are properly setup, and I enter a "confirm" frenzy, clicking it 6 times in less than 10 seconds.
And, of course, at the 6th click, slot ban. Hell, I was just filling one single plane! Yes, a single lone plane can fly 6 daily routes, that is 84 slots to reserve. Not even flying at night. Example, my current G-FAAG in current GW3. Flies From Edinburgh to Newcaste, Islay, Barra, Wick, Benbecula & Newcastle again. Every day. SX-FAB flies from Corfu to Vasteras, Preveza, Kefalonia, Tirana, Araxos & Dubrovnik each day(besides Vasteras on saturdays for the A check.). That's 82 slots to 6 different aiports, and I'm not allowed to validate all of them at once. I must first do some of them, assign them to the plane, then do the other ones, then assign the remaining ones. Very tedious, and it increases the risk of error & frustration.
NB : those planes make +250k$ per week before taxes and salaries(who are rather low anyways). My estimate is that they earn me around 125k$ per week, for a purchase price of 5M$(at the time of purchase, they're costlier now). Many people laugh at them, but under 280NM, they are insanely efficient(where slot prices are not too insane). So yes, I'd like to be able to plan them 6 daily flights at once without being slotbanned. Of course, I never had that problems with 737(4 maximum daily flights) or even RJs(5 maximum daily flights, Be it on CRJs, ERJs, A148 or Ejets). But it really annoyed me a lot.