It has varied. But the major updates initially revolved around sound and more recent updates have revolved around video.
Started in 1989 with a three channel setup, then over the next two years, moved to Dolby Surround (4 speaker setup), then Pro Logic (5 speaker setup). That system then carried me around 10 years. Though around year 4, I moved from Laserdisc to DVD. Audio sources during this entire time was exclusively CD. TV was a 4:3 aspect ratio Pioneer 29-inch CRT.
In 2000, we replaced the CRT with a rear-projection widescreen TV (Pioneer PRO-510HD). Though we didn't get the HD module. This worked out well for the widescreen-enhanced DVDs. New receiver let us enjoy Dolby Digital for the first time. Setup was 5.1
In 2002, we moved to a new home and we tried a 7.1 setup (though the rear two couldn't be placed in the proper locations, so this was really a 6.1 setup). Very little content played anything back there. In hind-sight, I wished I would have skipped the rear speakers and just placed our surround speakers to be in a rear position and not on our sides.
In 2009, we fully transisitioned to HD. i.e. was able to capture HD footage, edit it and play back on our system. As well as to have HD sources such as Blu-ray. The rear-projection unit died and was too costly to repair or update to HD. We thus moved to a Pioneer Kuro PRO141 Plasma.
Now in 2022/2023, we fully transitioned to 4K. New cinema camera to capture 4K footage, 4K Blu-ray player, all new speakers (B&W) and a new Sony mini LED. Marantz Cinema 40 will be here this week. Some 4K Blu-ray upgrades, but I have limited this to only very few titles (prob will end up with only between 15 to 20 total). Also, back to being a 5.1 setup with surrounds to the rear of the MLP.
Here are some averages on equipment lifetimes:
- Speakers: 20 years
- Subwoofers: 12 years
- TVs: 11 years
- Receivers: 9 years
Finally, the current B&W speakers (sans subwoofer), I fully intend to keep for at least 20 years, if not more. By that time, we'll most likely move to a smaller home after retirement and will prob scale down to a 2 channel system. Next TV will be micro LED (or whatever tech ends up besting that). Hopefully that won't be for another 10 years. And while I really like the premise of Atmos, not going to add any speakers beyond the 5.1 setup.