Ham radio operators under a rare call sign mostly work “split frequency” to efficiently serve as many stations as possible. The screenshot on the top shows this in practice: 3C0W from Annobon starts calling “up” on 10.119 kHz on the bottom of this spectrogram. Within minutes, a pile-up builds up, getting stronger in the number of stations as well as in width (“spread”). On the top of the picture, 3C0W requests a break (QRX), and most calling ceases.
The picture at the bottom shows just a 20 seconds’ clipping of this session. It is an excellent illustration of a sentence by the late L.A. Moxon, G6XN (author of e.g. “HF Antenna for all Locations”, RSGB Potters Bar, 1982, p. 216): “Communication in the amateur bands is usually restricted by interference rather than noise so one might argue that little would be lost and much gaines from a power limit of 30W, universally applied”. And even back in 1924, S. Kruse, the then-Technical Editor of ARRL’s “QST” wrote (May issue, page 36): “Practically none of us paid the slightest attention to making the signal redable or steady; no, the main idea was to make a noise.”
As you see, many problems still remain after nearly a century: people are calling when the DX station is transmitting and definitely cannot listen, and some station overdrive their transmitter in a way that they nearly bury the DX signal.