I've played from level 1 to SK-death a few times by now (fastest in <30 minutes), and came to a few conclusions, maybe others see it in a different way, but hey, this is a discussion board, so feel free to comment.
The question is: What can be tested with a max-level-13 char, and what can be tested with content up to the skeleton king.
Basically there are three types of monsters to fight against.
Type 1: 'normal' monsters, those usually die with the first hit
Type 2: 'blue' monsters, they take a few more hits, but usually die before they reach your character
Type 3: 'gold' monsters (and the SK himself), who usually reach your character before they die.
Now what skills do we have to use ?
Hungering Arrow ( auto-hits target)
Evasive Fire ( makes you jump back when you get hit )
Bola Shot ( +damage, no auto-hit )
Entangling Shot ( +slow, no auto-hit )
Grenade ( +damage, no auto-hit )
From what I've seen so far, the only skill I use at all is Hungering Arrow.
Reason: It does enough damage to kill anything (but 'gold' monsters) with one
hit, so the speed to kill monsters is (by far) the highest (due to me beeing able
to shoot anywhere into the vague direction of my enemy and auto-hitting
doing the rest).
There's no need for Evasive Fire, since I never have problems getting hit anyways,
no need for Bola Shot, since 'normal' monsters (which make 98% of all monsters)
die anyways, no need for Entangling Shot (since monsters can't reach me with
their full speed anyways) and no (real) need for Grenade (since I might miss
them due to lacking auto-hit, and I don't need the extra damage).
So all those other skills are pretty useless in my opinion. (At least in this stage of
the game). That means they won't get tested (at least not by me, and probably
not by a whole lot of others either).