Most GCC accounts benefit from separating English and Arabic campaigns rather than blending languages within one ad set, since audience behavior, creative response, and even cost efficiency commonly differ by language — bilingual audiences may see both, so overlapping structures can also cause internal competition and inflated costs.
Budget split should follow where your actual customers and search demand sit, not an assumed default — nationality, city, and category all shift the mix, and it is common to test both languages early rather than guess. Track performance by language, not just by campaign name, to see the real split of value.