Question on Tune Up Timing

https://dallasmdpc660.stonefielddigest.com/posts/heat-safety-steps-while-waiting-on-ac-repair-from-comfort-experts-in-a-north-fort-worth-heat-wave

Question on Tune Up Timing Does anyone know if spring or fall is better for a tune-up? Not sure when it makes the most sense for an older system in Summerfields, since the AC works hardest in summer but the furnace matters in winter