Someone asked what the average delay between first Beta update and then before it lands on Stable is. I can't say that for all updates, and just listed all Beta updates since 24th of June this year (about 5 months span). I also listed all other stable Regular and Major updates as well.
Let's look at the recent PC Steam Client stable Update news history: https://store.steampowered.com/news/collection/steam/
First set filters (untick [ ] Steam Client Beta to see stable updates only):

Note, the Regular Updates are the big updates I think. In the below list, I list all small updates until last Regular one, then continue listing Regular only. Ah, while looking through the list I found there are also Major Updates. I think these are the biggest ones. After first Major, I will only list Major too:
Small
- Today:
2026-10-16 (+3 days since last Small Stable)
- Small Stable:
2026-10-13 (+42 days since last Small Stable)
- Small Beta:
2026-10-13
- Small Beta:
2026-10-12
- Small Beta:
2026-10-10
- Small Beta:
2026-10-09
- Small Beta:
2026-10-07
- Small Beta:
2026-10-05
- Small Beta:
2026-10-01
- Small Beta:
2026-09-29
- Small Beta:
2026-09-27
- Small Beta:
2026-09-25
- Small Beta:
2026-09-22
- Small Beta:
2026-09-21
- Small Beta:
2026-09-18
- Small Beta:
2026-09-16
- Small Beta:
2026-09-10
- Small Beta:
2026-09-09
- Small Beta:
2026-09-06
- Small Beta:
2026-09-02
- Small Beta:
2026-09-01
- Small Stable:
2026-09-01 (+27 days since last Small Stable)
- Small Beta:
2026-08-31
- Small Beta:
2026-08-26
- Small Beta:
2026-08-18
- Small Beta:
2026-08-13
- Small Beta:
2026-08-11
- Small Beta:
2026-08-07
- Small Beta:
2026-08-05
- Small Stable:
2026-08-03 (+7 days since last Small Stable)
- Small Stable:
2026-07-27 (+5 days since last Small Stable)
- Small Beta:
2026-07-24
- Small Beta:
2026-07-23
- Small Stable:
2026-07-22 (+1 days since last Small Stable)
- Small Stable:
2026-07-21 (+28 days since last Small Stable)
- Small Beta:
2026-07-21
- Small Beta:
2026-07-20
- Small Beta:
2026-07-15
- Small Beta:
2026-07-14
- Small Beta:
2026-07-10
- Small Beta:
2026-07-08
- Small Beta:
2026-07-06
- Small Beta:
2026-07-02
- Small Beta:
2026-07-01
- Small Beta:
2026-06-25
- Small Beta:
2026-06-24
- Small Stable:
2026-06-23 (+13 days since last Small Stable)
- Small Stable:
2026-06-10 (+9 days since last Small Stable)
- Small Stable:
2026-06-01 (+5 days since last Small Stable)
- Small Stable:
2026-05-27 (+5 days since last Small Stable)
- Small Stable:
2026-05-22
Regular
- Today:
2026-10-16 (+151 days since last Regular Stable)
- Regular Stable:
2026-05-18 (+192 days since last Regular Stable)
- Regular Stable:
2025-11-07 (+367 days since last Regular Stable)
- Regular Stable:
2024-11-05 (+103 days since last Regular Stable)
- Regular Stable:
2024-07-25
Major
- Today:
2026-10-16 (+842 days since last Major Stable)
- Major Stable:
2024-06-26 (+378 days since last Major Stable)
- Major Stable:
2023-06-15 (+267 days since last Major Stable)
- Major Stable:
2022-09-22 (+1089 days since last Major Stable)
- Major Stable:
2019-09-30
"NO MORE OLDER POSTS FOUND." I reached the bottom, just like in real life. The duration for Regular and longer times are calculated with https://www.timeanddate.com/date/durationresult.html . BTW there were no Ai involved in making this post.
What is the conclusion? An average makes no sense here, as Stable Small Updates can be 5 days or up to 42 days. At least since last summer of this year.