Question on Tune Up Timing

https://garrettalct977.publishlane.com/posts/comfort-experts-furnace-repair-alongside-ac-repair-for-north-fort-worth-winters

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