I've been playing guitar for over 2 years now, I've been working on mainly technique and lately, music theory.. But I've never really got Time Signatures, etc.. I know what they mean (4/4= 4 quarter notes, 6/8= 6 Eighths, etc), but I've never been able to use them while playing. I just wanted to know, do most other guitarists actually count out the time signature as they improvise, etc?
tapping your foots always helps

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Well, I suppose you could count beats... for example if you're in 7/8 you count to 7 and start over... but mostly it's just a question of feeling the groove. I don't know of many people who actually count while playing.

If you're just dealing with 4/4 and 6/8, or well any time-sig with an even number of beats, the groove should be pretty apparent from the start. If not, a lot of these things just come to you sooner or later if you keep playing and listening to music.
Yeah, tap your foot and accent your playing on the beat.
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I usually count unless I'm comfortable. The problem is is that you don't have a "rhythm library" for those time signatures.

Grab some paper and just right out many rhythms that equal 5 beats and clap them out. Get them internalized. Start simple, then get crazy using 16ths and strange accents that you wouldnt find in 4/4. It's really fun. Do the same for 7/8 etc. This will help you immensely!
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Don't tell me what can be done, either.

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