  In this article, we investigate the real-world capability of the multi-link
operation (MLO) framework -- one of the key MAC-layer features included in the
IEEE 802.11be amendment -- by using a large dataset containing 5 GHz spectrum
occupancy measurements on multiple channels. Our results show that when both
available links are often busy, as is the case in ultra-dense and crowded
scenarios, MLO attains the highest throughput gains over single-link operation
(SLO) since it is able to leverage multiple intermittent transmission
opportunities. As for latency, if the two links exhibit statistically the same
level of occupancy, MLO can outperform SLO by one order of magnitude. In
contrast, in asymmetrically occupied links, MLO can sometimes be detrimental
and even increase latency. We study this somewhat unexpected phenomenon, and
find its origins to be packets suboptimally mapped to either link before
carrying out the backoff, with the latter likely to be interrupted on the
busier link. We cross validate our study with real-time traffic generated by a
cloud gaming application and quantify MLO's benefits for latency-sensitive
applications.
