At most, we recommend one conjugate every 5-10 bases. Theoretically, we can place a conjugate at every location and at the 3’ and 5’ ends. Unfortunately, it is very difficult to synthesize these types of compounds and just as difficult to analyze for labeling efficiency. In many cases, the resulting products are essentially insoluble. In other cases, such as fluorescein, the dye actually quenches itself if too many are present, becoming almost non-fluorescent. The length is also limited.