As I said above my group is hitting the limit easily with lower tier quests and we don't think we are rushing. Why would I not do 3 quests back to back if they are just 100 meters apart? And doing 3 tier1 or tier2 with 4 people doesn't even take half a day. And I do like early game, so I don't really want that we are swimming in concrete by day 14, for example.
I actually don't see a problem in having to wait till day 4 to get a bicycle. Obviously the game is intended to make us walk for a bit of time (what else would Cardio be for?). To make us appreciate the bicycle, to give us a progression from foot soldier to cyclist, just like we are progressing from really awful pipe weapons to guns. For a game that is intended to last for say 40-60 days 4 days seem a good duration to me.
Just as comparison, and this is only single player, I had less than 1000 concrete altogether in my game so far and am on day 15 with 2 hour days. I'm most definitely not swimming in it.
I think they main thing to consider with this restriction is whether or not it is good for new players to restrict their questing progression rate. Is there a legitimate reason to restrict new players to 3 (the current default)? Roland said to get players to do other things, but as I pointed out, doing those other things on for and with low quality some tools isn't likely to make a new player want to keep playing the game. I know I've personally stopped playing games that might have been great games because the initial gameplay was too grindy. So I don't think that is a good reason to restrict new players. Is it too make the game last longer? Maybe. They want that. But it is an artificial way to do it and it really only affects the first few days because questing isn't required to process and it is really just slowing down getting a bike. Is that worth restricting new players? Is there some other reason to restrict them that is more legitimate?
The way I see this restriction is that it is for veteran players far more than new players. Veteran players are the ones who want more challenges, different gameplay, new things, restrictions, and so on in order to keep the game feeling "new." But veteran players don't need this as default. They can switch the setting easily enough. New players may not know how to switch the setting or that it even can be switched. So I think the default is better at 5, which most new players aren't likely to hit and so won't be restricted.
Also, although I have nothing to support this, I have a feeling that the average new player will complete the initial intro quests that will bring you to the trader and then the trader offers them a quest. They will probably complete that and when they turn that in, they will not be told to go mining or farming or exploring. They will have the options from the trader to buy/sell stuff or to quest. I think most will quest. And likely continue to do so for the rest of day 1. A restriction will feel out of place, especially when the trader has more quests available.
Yes, the challenges can get you doing other things, but they are set up in a way that feels like just general goals and not really a roadmap to follow. So I do think new players will quest all day on day 1. If the goal is to get them to do something else, I don't think restricting progression of quest tiers is how you do that.
Either way, it doesn't matter to me. I set it to unlimited just so I can avoid ever having to see the obnoxious red warning icon that never goes away until the following day. Since I have the option, I don't really care. I just think it is better at 5 than 3 for default settings for new players.