[RPG] How many times may a character attempt a skill roll for the same test?

How to Use Skill Points

The maximum number of skill points a character can put into a skill is equal to his current level +3. Each skill point buys 1 rank of a class skill or 0.5 ranks of a cross-class skill. Anyway, I suspect if the ranger has too many skill points he's not putting the maximum number of skill points in his skills.

Sample Skills for a Human Rrg2 with Int 14
The human Int 14 Rgr1 has 6 skill points granted by his class (PH 47) and 2 granted by his Intelligence modifier (PH 9). That 8 is multiplied by 4 at level 1 for 32 skill points. As a level 1 human he also receives 4 skill points from his racial trait (PH 13) for a total of 36 skill points. At level 2 when he takes his second level of ranger he'll receive 6 skill points from his class, 2 from his Intelligence modifier, and 1 from his human racial trait for a total of 9 more. That's a grand total of 45 skill points as a Rgr2.

The following is one method of spending all of these skill points.

• Bluff [4 skill points but a cross-class skill so only 2 ranks]
• Handle Animal [1 skill point thus 1 rank]
• Hide [5 skill points thus 5 ranks]
• Knowledge (dungeoneering) [1 skill point thus 1 rank]
• Knowledge (nature) [1 skill point thus 1 rank]
• Listen [5 skill points thus 5 ranks]
• Move Silently [5 skill points thus 5 ranks]
• Search [5 skill points thus 5 ranks]
• Sense Motive [4 skill points but a cross-class skill so only 2 ranks]
• Spot [5 skill points thus 5 ranks]
• Survival [5 skill points thus 5 ranks]
• Tumble [4 skill points but a cross-class skill so only 2 ranks]

Explanation
I picked the skill Bluff as it's both used to create a diversion to hide (PH 68) and one of the skills to which the ranger's favored enemy bonus applies, as is the skill Sense Motive, which I also picked. I didn't pick the skill Balance because having 2 cross-class ranks in the Balance skill isn't a worthwhile investment compared to the 5 ranks in Balance that the character will be able to put into the skill at a later level.

The skilled city dweller alternative class feature (available here) allows a ranger to trade the following class skills: Handle Animal for Gather Information, Knowledge (nature) for Knowledge (local), Survival for Sense Motive, and Ride for Tumble. Trades aren't made all-or-nothing group but can be done individually. Trading the skill Ride for the skill Tumble is an especially good deal in most campaigns.

This is how skills are supposed to work!

If you are in a situation where there is only one person doing something, and they are rolling a single skill check, then yes, this is how it's supposed to work. Giving help is a natural thing and should be used in situations like this. There is no reason to prevent it unless the task is clearly something that's not going to benefit from someone else giving you assistance. There are some things you can do to limit it.

It's also worth noting that helping can often save you some table time. As a AceCalhoun points out in the comments, in many cases what happens if you don't help is that everyone in the party tries their hand at the task. This behaves very much like advantage, but with a slightly lower overall modifier (because most likely you'll have one character who is good at a task and the rest that are lower). So Working together only raises the change of success slightly and consumes less table time in these cases.

• Be a bit more stringent about what you allow for assistance. Is coaching stealth really all that helpful? do you really want someone looking/talking over your shoulder while you're picking that lock? Evaluate situations where characters attempt to aid more carefully.

• Have more than one thing going on at once. If all the characters need to be stealthy, they can't be helping each other. And if you need two arcane characters working on the sigils on opposite sides of the room, maybe they have to choose which one gets help from the third (or don't have anyone to help at all).

• Make things take multiple rolls and limit helping on all of them. Maybe the first roll the wizard can be helped, but after that he's on the other side of the trap, or arm deep in the sigil or something to where additional assistance isn't going to help him.

• Figure out how to inflict disadvantage for the task. Maybe there are mitigating circumstances.

• Create a distraction. A rogue can't help the wizard if he's busy fighting baddies. Make some skill checks happen in an occupied room. Make completing the skill checks the win condition rather than defeating the enemies.

The basic crux of all of this is that helping is supposed to a mundane task that provides advantage. Yes, that's a huge deal, but it also doesn't stack with other things that give you advantage and it can be easily cancelled by disadvantage.

So get creative! Build some situations into your adventures that prevent your heroes from helping each other (or make the opportunity cost higher). But don't do it all the time, that might get tiresome. Adventurers like to help each other out, let them, but don't make it easy all the time.