I mean it does vary somewhat, but if you play every day, practice right, and take some time to just noodle a bit to warm up your hands before you start the serious stuff, you should be pretty consistent.

Stuff like temperature (cold, stiff, numb hands - warming up helps a lot though) and fatigue can have a more dramatic impact even if you are practicing regularly.
Quote by H4T3BR33D3R
Youre officially uber shit now.

Quote by StewieSwan
3d9310rd is far more upset than i 
yes but it gets better as you go along. i can play say a E chord in my sleep and have it be correct so i'm past the basics so to speak. onthe other hand more complex stuff sometimes doesn't go as well. i think everyone has "those days" occasionally.

i've always maintained that a good way to measure progress isn't on your best days but rather your worst. as you go along what you consider to be a crap day will be better than what you considered to be an awesome day say 5 years ago.

but yeah i have crap days where i'm just not feeling it. on those days i just put the guitar down and try again the next day.
it's only you
Quote by Kevätuhri
Hail isn't too edgy for posts, posts are not edgy enough for Hail.

Quote by UseYourThumb
You win. I'm done here.
every day is a bad day when you're no good
There's no such thing; there never was. Where I am going you cannot follow me now.
I'm literally waiting for the day when a zombie army consisting of Jimi Hendrix, Rory Gallagher and SRV will rise up and eat my brains for butchering their classics on a regular basis!

On a more serious note though, yeah i have good and bad days but I just try and ensure that I at least get something it out it. For instance I may be practicing sweep picking and for whatever reason it feels like I'm trying to play the guitar with boxing gloves on. I'll just switch to something else like just playing barre chords for 30 minutes and that way I'm still developing on the guitar, even if it's not what I actually set out to do.
GUITAR COMPANIES - Contact me if you'd like to sponsor my signature!
some factors to fight "bad days" stay in shape health wise..keep your mental attitude positive and fight being judgemental of others and yourself...bad days could be a combination of these factors..learn how to overcome them quickly before they settle in and you accept them as "that's the way it is" .. reward yourself when you recognize improvement in your playing..then move on..keep learning new and more difficult material..if your a "musician for life" this type of advice is necessary..don't compare yourself with other guitarists and say "they don't do that'..we really don't know how other people "really" feel..you may think they just played a super solo...they may think they are having a "bad day"
play well

Quote by gweddle.nz
The kind where you just can't seem to play anything right? Even basic stuff?

Yep, we are all different every day. Roll with it.
"Your sound is in your hands as much as anything. It's the way you pick, and the way you hold the guitar, more than it is the amp or the guitar you use." -- Stevie Ray Vaughan

"Anybody can play. The note is only 20 percent. The attitude of the motherfucker who plays it is 80 percent." -- Miles Davis

Guthrie on tone: https://www.youtube.com/watch?v=zmohdG9lLqY