Mindless spamming will not get you far, when you are alone, or at least it will slow you down (either by having to fight longer or spending some time in downed state or having to re-portal to a way point). You will use your skills #1 on auto attack (kiting repositioning, if you play well), your skill #2 probably on recharge and #3-#5 wisely.
e.g. Fire/Staff #1 Fireball - #2 Lava Font (you have to know where to put that small AoE spell, if displaced it is useless) - #3 Flame Burst on really dangerous groups of enemies (just blasting an area can be useless or less effective) - #4 Burning Retreat is wasted on recharge, as it is your get away from melee foes skill (& kill them if done correctly) and finally #5 Meteor Shower with its huge AoE radius can be wasted if put into the wrong spot. After that you have to wait 30 sec for the recharge.
Clever swapping of attunements on my Ele worked very well adventuring alone. Having a partner was better in a few situations, because someone could always fall back and revive.
I had the impression that some "wildlife" needs a little tweaking with their respawn times. There was a cave filled with spiders & a skill point challenge I could not master, because I got overwhelmed by the fast respawns, no matter how fast and efficient I had become at killing them