In Year Zero games you are not suppose to roll to often.
Extract from textbox p.44
<> you should only roll when absolutely necessary, in dramatic situations or tough challenges. In any other situation, the GM should simply state that your action succeeds.
When it comes to pushing, you are only allowed to push if additional successes will increase the effect of the roll in some way. The GM has final say in this.
When it comes to Lead the Way and Make Camp, both of those will happen regardless of how many successes you get, and as mentioned above, the only thing that successes does is to avoid (unknown) mishaps. According to RAW, you are probably allowed to push these skill rolls, but you can also interpret that it is not possible to push a skill roll that takes a quarter day to perform against something that is unknown. It isn't RAW exactly but it isn't that far off either.
Also the player is suppose to describe, not only the normal skill roll, but also if he pushes the roll, what the character is actually doing. This is something that may be forgotten sometimes that the character is making the action and the push, it isn't just something that the player is doing and if the player can't describe what the character actually is doing when wants to do an action or when he wants to push, then that is a reason for not allowing the skill use or push in the first place.