I have yet to see a reason to install keep alives en mass. I have one tiny loco that potentially could have problems even with powered frogs, but it came with a factory installed keep alive. It runs WAY too long before the charge runs down, but that’s a different subject.
If you use powered switch machines, besides basic Atlas Snap Switch type, powering metal frogs is essentially free by using the contacts - there’s no need for an exepsnive (relatively) frog juicer for basic turnout installations - simple sidings, passing tracks, etc. The whole reason they were invented was to handle proper frog polarity in complex junctions where tracks cross through turnouts and you might have turnouts inside turnouts - see the CNJ Bronx Terminal layout of Tim Warris. Frankly, I would throw my hands up at such trackwork and look for an automatic electronic device as well.
I have yet to have an issue, with two layouts since going DCC and having sound, that would justify putting a keep alive in all or even the majority of my locos. With frequent feeders, I have no power problems. Even the club layout - the only power issues are on the older modules that use fitter tracks, a keep alive would help there, but the right way to fix that is to either power those sections or do like are newer modules do and not use fitter tracks connected electrically only by rail joiners that get used over and over.
I’ve a beliver is avoiding issues rahter than masking them - a frog juicer works by detecting the short ont he frog and fixing it. Contacts on the switch machine work by never having the short in the first place. Same with autoreverses. Like a frog juicer in a complex track arrangement, an auto reverser can really help out. But in more trivial situations where the loop point is obvious - you can avoid the short entirely. I may end up with some frog juicers on my layout - but certainly not for every turnout, most will be switched via contacts. Unless something drastically differn