"Lady Executive" Hotpoint washer
I never owned a TL with soak function, but they were available in higher end units (I always bought basic or low-middle range units). There is a recurring ad that unimatic posts from time to time under "Picture of the Day" which features a Hotpoint "Lady Executive" washer with auto soak (soak overnight, then goes automatically to a wash cycle, plus there was option for extra rinse). This model, based on the model's clothing and artistic design of the ad, seems to be from the late 1960s or maybe 1970 at latest. So the soak function was available even 40 years ago, but probably not on entry level models.
The Hotpoint ad mentioned an eight hour soak which they called "overnight soak". The ad seemed to be aimed at the new generation of working American women: the late 1960s and 1970s saw women stop being stay at home mothers and begin to have jobs and careers. These settings allowed a working woman to wash a heavily soiled load overnight, and she did not have to be home (or awake) to manually advance the controls.
Hotpoint as I understand it was the lower priced "value" line made by GE, so I think it's reasonable to assume that GE-badged models offered the same options, if one was prepared to spend money. Or maybe not: since Hotpoint was a value-priced, "young family" brand, maybe they offered the extra options only on Hotpoint, in the belief that single women or two-income families would look to Hotpoint to save $ rather than consider GE. Single-income families with higher incomes (so that mom didn't have to work) presumably would have had less interest in a washer that automatically shifted from soak to wash cycle. Either mom was home to do the task, or they had a housekeeper do it.
If someone set it up after, say, supper time, it would soak eight hours overnight, then automatically advance to wash around 4:0o-5:00, and when the women woke at 6:00, the load would be ready for the dryer. Almost as I use the Delay Wash feature on my FL today----if I set up at 20:00 or 20:30, the load completes by 05:30 and is ready for the dryer. The difference today is my FL's higher spin speed and shorter drying times. I need only 30 minutes to dry a load of permanent press, including the cool down time, but back in the "Lady Executive" Hotpoint days, most likely a similar load had not been spun as quickly and would have needed more than 30 minutes to dry.
The Hotpoint in the ad even had a "wash twice" option on top of the Soak function, so I assume there must have been three compartments for adding detergent: one for Soak, and one for each of two washes. Add extra rinse on top of that and you would have filled the washer FIVE times (not all hot water, but still...). That a LOT of water.