That's why in Book 3 of the method, I talk about how to construct bass lines from chord symbols. It's what we have to do much of the time - but by Book 3, you're already reading 16th notes!
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JUst picked up book 3, based on the reco the series is getting in here. I am another happy customer.
16th notes were my main area of weakness, well 16th note rests to be exact, and the 3rd book is really helping me out.
Seems to be well paced, with a good mixture of notation only & tablature included exercises.
Each exercise is just that little bit to hard, but close enough to know that with a little practice it will be in reach. This keeps the motivation and the improvment up.
One of the better books I've seen. If you're planning on teaching yourself, or have one of those teachers that are happy to take your money and watch you teach yourself, I'd be looking at these books pretty closely.