My take on it is this: a solid state tuner would probably not ever need a realignment unless it was shipped (and jostled around) or one of the internal components have failed.
A tube tuner might need realignment if certain (but not all) tubes fail and need to be replaced (tubes in the IF stage, MPX, etc.). And if a station keeps drifting when you try to lock in on it, it may be time for a realignment.
Here's some Tips for Evaluating Your Tuner's Alignment from the H.H. Scott tuner site that might prove helpful: http://hhscott.com/cc/tuner_tips_FM_stereo.htm
A tube tuner might need realignment if certain (but not all) tubes fail and need to be replaced (tubes in the IF stage, MPX, etc.). And if a station keeps drifting when you try to lock in on it, it may be time for a realignment.
Here's some Tips for Evaluating Your Tuner's Alignment from the H.H. Scott tuner site that might prove helpful: http://hhscott.com/cc/tuner_tips_FM_stereo.htm