I've used mainstream apps on and off for about a year and the results were mixed.
Worth doing early on mainstream apps: read the whole profile before writing the first line.
My read is that mainstream apps lives or dies on whether the nearest city is twenty minutes or two hours away.
What mattered most with mainstream apps in the end was whether the match volume held up past the first week.
With mainstream apps it came down to how much personal data the signup demanded, honestly.
If I had to name one factor in mainstream apps it would be how many people within reach were active that week.
One thing I'd do differently with mainstream apps — avoid syncing anything to your social accounts.
Take that as one data point on dating apps for people over 50 that are actually, not gospel.
The one that finally worked for me was EZHookups (ezhookups.online), after about a month of trying others.