I would do a little science experiment in your yard with enough posts to see what you can get away with. There are a couple of oddball variables with fence tape because some of it has a lot of stretch and some doesn’t have much.
It also depends on what your plan is for corners? This is the part that takes all the stress and the size/quality of your corner turns determines how tight you can pull the fence, even with tape. Drive steel posts or do you have an auger for wood corner posts?
When I helped with cattle fencing, the guy I worked with wanted 50 foot spacing on electric fence with tape on average. But then the terrain and the stability of the corner would dictate a lot of what you did. I would GUESS that on average the true post count when compensating for terrain was one post every 30-40 feet on average.
Don’t use too many posts for fence to keep out deer. My parents have their whole yard and garden e-fenced off and they made the mistake of putting in too many posts so the fence was too rigid. Deer are hyper and when they get zapped, they jump forward. If the fence is too tight these means they just snap the wire or otherwise CF the fence if there’s too many posts, but if there’s give, they recover and reverse course before snapping the fence or pulling it off the posts.
Post some pics and update us on how this works for you!
Grouse