Is there any penalty for "wasting" time in IWD? I mean, what is keeping me from resting anywhere for days upon days other than the possiblity of encountering enemies? Is there any reward for reaching certain locations quickly or can I just ignore this mechanique altogether?

No impact whatsoever.

In the second game, "wasting time" can actually become pretty important, if you're playing as a drow or duergar and get a penalty during daylight hours. Other than possible injury to your (the player's) eyes, there's no reason whatsoever for you to ever see the sun.

I replied to your PM, but I'll reiterate here as well in case others wonder about it.

The game only heals you by 1 HP every few hours (can't remember the exact formula, but I think it may be 1 HP per day) when resting, which is why you see ridiclulously long rest times when you're injured. However, if you have a healer in your party (Cleric, and possibly Druid), the game assumes that healer will memorize healing spells and heal evryone through magic. This cuts the resting time down drastically (to as little as 16 hours).

hi thx for ur help, but i still cant explain, why tiz not always happens - i played 2 years ago and had never a healer in a group, resp. i was fighting til a was totally alamost dead plus i used already all the spells and still i got no more than 16 h resting time. the same last week - i installed the game was playing and everything waz ok - i was bleedin like hell, my character wasnt any kind of a healer and i didnt get over 16 hours. but i didnt like my character so a deleted it and created new one and got tiz shit... like fuckin 2 days sleep on 1level :( i dodnt wanna see it when i am at health 100 or more.
and at least its totally anoying when u killed somebody but have to run away to rest and u cannot collect the stuff they dropped... and also in the ice temple - u got no chance to rescue the prisoners before gettin sacrified because the kill one each day - so if i am gonna rest for 50 days - there is nobody more left to save and that means - no extra XP... :(( - its realyy irritade me - why tiz happens after a second time i created my charcter???
thx

Check your configuration. There should be an option to 'rest until healed'. Disable it.

hi, i know bout that, but when i disable tiz and i dont have any healer in my group how i gonna heal, if i dont have any elixirs?
i am building up a 2lv rouge/ Xlv wizard - i need the spells get recharged...

so the basic question iz - if tiz iz normal to get so insane resting times and why tiz not always happens - i went 2 times through the game with almost no healing spells - only thx to resting - never get over 16 / 24 hours resting time...