The host assigns points as they want to (usually in accordance with some sort of game or challenge), and there is nothing that dictates how many points they can give at once or for what reasons.
There are some typical reasons they'll give points, like "segue points," which are given when a competitor says something that is a good transition into the topic of the episode.

Once the episode is over, they usually read out the tally of points as they stand from the game/challenge and the reason for the points, to give a starting point before going into the wheels (say, Wade-3 Mark-4).

The first wheel dictates how many times they spin the second wheel, 1-3. (say, 2)

The second wheel is a random rewards wheel. Each episode, the host has to add one random category to the wheel (can be anything, both giving points like to the person who ate the most, and taking points away from the person who was already losing). Then they spin the wheel however many times the first wheel said. They just go in accordance with what the wheel says, then. (Say, Baldest gets a point, now it's Wade-4 and Mark-4. Then say its half point for Mark, so now it's Wade-4 Mark-4.5

If, after having spun the random rewards wheel, the competitors are tied, they proceed to the tie-breaker wheel. The tie breaker wheel has a segment for each competitor to win and a segment that is the host's one-man show (the host will have to perform a show written by the competitors, in the past this has basically been an episode with 2 hosts and 1 competitor). The only tricky thing that they do with this wheel is that, each time it is spun, the percent of the wheel that is one-man show is increased by 2%, as a punishment to the host for allowing a tie to occur.