a little more ...

Another useful reference to the pros and cons of straight ahead and pose to pose:

Animating: Pose to Pose + Straight Ahead

Both have their advantages and problems. The best approach, then, can be to mix them:

Hibrid method

1. start with Pose to Pose;
2. in one of next passes, maybe only for certain key parts that don't look good with software interpolation, return and fill in between the already keyframed poses, animating straight ahead, substituting the interpolated data by new keyframes.

Good points:

• unites the best of both worlds;
• avoids the main problems with each method when used alone;
• can give a wealthy mix between tight control and creative freedom.
• Pose to Pose is a good overall method, but Straight Ahead is better for faster actions (so an animator may end up doing frame by frame on such parts);
• Straight Ahead is not a good idea for mechanical motion and anything that can be interpolated well with animation curves, for which Pose to Pose works very well.

Bad points:

Actually, nothing not present already in the two methods:

• requires planning for the Pose to Pose part;
• it's probably slower than using Pose to Pose alone;
• gives a little more chance for pitfalls in the Straight Ahead parts, though probably in much smaller and easier to fix steps than when using Straight Ahead alone.

taken from : straight ahead and pose to pose