I'd get a real razor over the disposable if you go the wet route.
I just keep a little fuzz around the sides and use a Wahl beard trimmer with the shortest guide. Not sure how well it would work to make it smooth though.
I just copied down my head number and may try a new head to see how it works as it has been maybe 3 years. With current razor which is apparently water proof as you can shave in the shower if you want, I just shake the stubble out, rinse it off when open, then close it and dip running razor in shallow water to clean it out.
Older models, I would remove individual blade and receptacle, brush off and replace same blade in same receptacle. I figured mixing blades and receptacles up might be mismatch as wear was different.
I would think that shaving both head and beard would be maybe 3X the surface area of just beard so head life may only be 1/3.
I'm not confident of any electric razors that can stand up to shaving a head. I used mine a few times but it simply took too long and I had to continuously go over same areas.
I buy a package of disposables from Costco and use one blade per month shaving my head four times a week in the shower. Thus, that's roughly 12 head shaves a month.
I forgot the exact quantity of razors but I think 26 for roughly $23 which gets me just over two years. IMO, that's the best deal I'm gonna find.
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