It is good practice to have the rafters aligned on both sides of the ridge. That way the horizontal loads are transferred from the end of one rafter to the opposing rafter directly through the ridge member so the ridge member is simply being pinched between the opposing rafters.

If the rafters are not aligned the ridge member is placed into bending and shear between the rafters. In this case the ridge member must be designed to resist the bending and shear stresses. Where a 1X ridge member may be perfectly fine with the rafters aligned on both sides it may be woefully inadequate when the rafters are offset by 8". (That's the midpoint of the typical 16" spacing.) If the ridge member has a large knot located where the bending or shear stresses are high it has a greater chance of failure.

Very often the bottom ends of rafters are nailed to the ceiling joists so the ceiling joists will prevent rafter spread. To be able to nail the rafter to the joist the opposing rafters cannot have more than a minimum offset.

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"Baseball is like church. Many attend but few understand." Leo Durocher
Bruce Breedlove
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