do you mean the delves? group delves are easily soloable by powerful builds, or builds made for soloing. if you arent too survivable yourself bring a friend, maybe a healer, 2 should be plenty if you cant do it alone.
Playing your character the way your character should play is all that matters. Play as well as you can but never betray the character. Doing so would make playing an mmoRPG pointless.
I'm currently trying to complete solo all 7 group delves with different builds on PTS.
Not very surprising, till now, this has been rather easy with a magplar. Doable, but not so easy with a B/B stamplar. I used also DW with the latter one: slight improvement in survivability (blood craze, etc), but way more boring for the DPS.
I'll assume you mean the group delvs... the larger delvs with lots of bosses and adds...
Well, I think with 2 you will get max XP, if that is what you mean, its also significantly easier... although they are overland so it can all be soloed. Nice to have someone to chat with also
Craglorn is weird. Some of the Dungeons act like Delves in that other players not in your group can come in while you are there. Some of the Delves are Group Dungeon Difficult.
Some of the Delves/Dungeons are easier than others.
I would duo them as that gives you the best Experience, and smoothes over the rough spots.
Skyreach, depending on how you pull things, you may not be able to duo.
Enjoy the game, life is what you really want to be worried about.
PakKat "Everything was going well, until I died"
Gary Gravestink "I am glad you died, I needed the help"