Pendulums or overshoots

The system swings past its target and overcorrects because feedback arrives too late or too strong.

January: you feel broke, so you slash everything, no restaurants, no coffee. By March the austerity feels unbearable and you swing into a spending spree, which triggers panic, which triggers another lockdown. Your bank balance looks like a seismograph, oscillating around the budget you actually want.

Pendulum behavior is the signature of feedback that arrives too late or hits too hard: you correct based on old information, overshoot the target, then overcorrect back. To use the cue, first mark the target you keep crossing, here a monthly spending level. Second, find the delay: how long between spending and actually feeling its consequence? A statement arriving 30 days later is a long lag. Third, gauge the strength of your reaction: total lockdown is a maximal response to a moderate error. Long lag plus strong reaction gives you a candidate explanation for the swings, and the fix hunt shifts from willpower to timing and dose. Rule out the rival first, though: some oscillations are just seasonality or alternating outside events, like holiday costs, not overcorrection at all, and no amount of retuning yourself will smooth those.