Yes, during the summer months, the daily total CAN reach and exceed 2,000 pilgrims per day. I have worked at the Pilgrim Office as a volunteer each summer since 2014, including the weeks straddling the Feast of Santiago on 25 July. I will do so again this year. THAT is when you want to avoid arriving in Santiago. Every bed is booked FAR in advance.
But, choosing when to walk the Camino, is in my view similar to surfing and sitting on one's board beyond the breaking waves to choose the RIGHT wave to ride. Using this metaphor, each wave is a surge of pilgrims. You want to ride in the trough of the waves, not at "peak wave." But the surfing metaphor holds true.
For example, there is usually a surge or wave leaving each major terminus or starting point along the Camino each Sunday and Monday. This includes St. Jean Pied de Port, Pamplona, Burgos, Leon, Ponferrada, and Sarria on the Frances. On the Portuguese, Porto and Tui are popular starting places.
This surge or wave progresses down the Camino at a relatively constant pace. The wave of pilgrims DOES tend to stretch out as the days progress. However, and as a "rule-of-thumb," a pilgrim who started on a Sunday at Pamplona, will likely arrive at Santo Domingo de Calzada the following Friday evening. The particularly applies to the majority of pilgrims who follow the 33
Brierley stages. This wave causes a unique demand on accommodations, both reservable (hotels, hostals, private albergues) and first-come-first served (municipal or public albergues).
Similarly, folks starting at Leon on a Sunday, will tend to arrive at O'Cebreiro the following Friday evening. If you know this spot, you know there is no room at the inn over weekends, as it is a popular place for tourists to visit as well as pilgrims.
This pattern follows through down the entirety of any Camino route. It is most apparent once one reaches Sarria. From there to Santiago, the flow on the Frances is the heaviest.
My advice to pilgrims coming from the East of Sarria is to arrive there from Monday through Thursday evening. This places one wave of pilgrims in front of you, and another behind you. It increases your chance of obtaining your choice of lodging until you reach Santiago. However, it is NOT a guarantee.
Additional considerations, starting in May, include the newly emerging popularity of university student groups on a course that includes walking some portion of a Camino. For most of these organized groups this means from Sarria to Santiago.
The only problem with this facet of the pilgrim population is the demand they create on hotel and hostal accommodations on the route. One group, even if sharing rooms, can easily fill a given location, on any night of the week. The normal wave pattern does not always apply to these sponsored and organized groups.
So, even if you follow the "rule-of-thumb" to avoid the successive weekend-related waves of individual and small groups of pilgrims, you still have to contend with organized groups or students, and other "tourigrinos," who hire tour companies to provide them with the "authentic Camino experience."
I am NOT being critical. I AM merely stating facts as I know them to be.
The only way IMHO to avoid the summer surge from June through September, including the May student groups, and tour groups throughout the season is to walk "off season." For this reason, I and many other veterans choose to walk in the two "hip seasons."
The front season starts about one week after Easter to give those holiday-vacationing pilgrims time to get in front of you. Then, we try to get off the Camino by about mid-June, when all the schools let out and the now free students and others with time off can do their pilgrimages. We simply accept and cope with the competition for beds by the organized May student and tour groups.
The end season starts around the middle of September, after all universities have gone back into session, and continues through the end of October, into early November. The numbers of pilgrims are far lower. The weather is still quite pleasant, and you have entire stretches of Camino to yourself.
The final point is that you need to pick your starting date and location with the above in mind then start to pre-reserve accommodations, unless you are of the group that prefers to walk into a hamlet or village and trust that an albergue will have a bed for you.
I agree that this planning ahead bit DOES spoil some of the spontaneity. But, as Rule One states, each pilgrim walks his or her own Camino. It is not for any other to judge how you choose to accomplish it.
Personally, I have had too much drama in my life to date, so I eschew creating more excitement and uncertainty. Plus, I am too settled in my ways. So, I plan ahead, book a room or bed, and SHOW UP!
I hope this helps.