I would imagine keywording issues are largely the same as for photos, but if this isn't true, then ignore everything I'm about to say.
You really shouldn't care about the total number, just that you got (a) all the critical ones for that subject, (b) regional variations in how something is described - such as a garden in British English versus a yard in US English; (c) careful use of multi-word keywords and their components - so "baby boomer" is fine, along with older, mature, etc. but don't use "baby" and "boomer" separately; same for "New England".
You want your work to be found, but not to show up in searches where buyers will wonder why on earth it's there. Simple subjects only require a few keywords, but multiple people in a particular town (with landmarks showing) could easily require more than 50, so you need to prioritize.
A useful tool on SS for images looking at your top performers list where you see the important keywords that led to a sale. Nag them and the other sites to include that info for videos (it's been saying "not for video" for eons) as it's important insight. For example, I always include both house and home, but house is way more frequently the buying keyword - even when home shows up in the list, it's less than half the percentage of house.
Mostly, learn to think like a buyer and don't worry about keyword numbers so much.