hard to say, it depends on how they scale to be able to say how tactical you need to get with them.
right now at lvl 10, i do lay down fire traps in choke-points i now mobs will have to go through...but i also just lob them at mobs liek they were grenades too.
one other cool note, i was parting with miz and he got a totem that caused aggro, so was really cool for him to set one up and then i laid traps on it

but you cant "spam them" as far as i can see currently. right now i can only have 3 on the ground at any one time and they do have that cool down timer.
i think i will test bear trap next (snare) i think i have one as a quest reward.