How many skill trees should I focus on for a thief?

[Daelon DuLac]

I'm guessing it takes a huge amount of time to get even one level when you're that high though.

It really depends on how you do it. It does take longer at higher levels, but I use the Alchemy thing all the time to add points to get to the new level and magic works as well (any of the schools I've found, especially when the numbers are relatively low on them). It still takes longer, but you can level up pretty quick, even at higher levels. I'm in the mid 50's now and my weapons skills rarely point up at this point, but I can still get my Alchemy and now my heavy armour since I legendized it.

 

[coinop25]

I'm guessing it takes a huge amount of time to get even one level when you're that high though.

It's definitely slower, but some skills level faster than others. Block levels REALLY slowly. Illusion and Conjuration level fast. I got bored enough over level 75 that I used an exploit to gain levels fast by speed-leveling Alchemy (fortify restoration loop). But something like One-Handed levels pretty fast once you set it to 15, assuming you use it a lot in fights.

One thing that might make things easier for a Thief is to make Sneak legendary and just lean on powers, gear, and spells while it levels up again. Thanks to all the gear and special spells unlocked from Thieves Guild quests, you should be able to turn invisible, muffle yourself, and so on, making it easier to remain undetected while you level up the skill again (and it doesn't take too long to get to the "Silent Roll" perk again, which is the main one I notice missing once I can't use it...).

 

[Morgan]

I'm guessing it takes a huge amount of time to get even one level when you're that high though.

I guess that's why I hardly ever get past level 12 or so.