The type of product would not effect buildup; however, the amount of cyclomethicone in a product would.
For example, a conditioner that has cyclomethicone as the 10th ingredient is going to have less of it and will buildp slower than a conditioner with cyclomethicone (or cyclopentasiloxane, more commonly) as the second or third ingredient. Likewise, if a serum is primarily dimethicone and cyclomethicone is lower on the list, it would buildup slower than a primarily cyclomethicone serum like Frizz Ease.
Conditioners generally will have less cyclomethicone than a serum because it is a heavier, more substantial cone. Conditioners are more frequently having cyclopentasiloxane as the second ingredient after water, and these would build up slower than a cyclopentasiloxane serum that has cyclopentasiloxane as the first ingredient.
Silicone Cyclomethicone Water soluble? No Recommended cleansing agents cocamidopropyl betaine, cocobetaine, other mild surfactants, or conditioner washing