It depends on what I am doing. I like to clear cut a zone, picking up all tomes, skyshards, quests, and harvests as I go and mounting is more a waste of time this way. If I am lead or treasure chest hunting only, I will use my mount more.
My character is a horse-crazy elf and too small to see over tall grass - so she rides everywhere she can. One thing we've been very pleased about is that once you have max speed on a horse, its walking speed is a very pleasant clip - much faster than my elf can walk but much slower than her very fast horse can run. It allows reasonable progress on getting where you want to go but really allows time to enjoy the view and notice more details.
True end game is getting all of the speed perks on your mount, only to end up riding it in a roleplay-walk so that it trots along at a decent clip xD It ends up being fast enough to make you feel like you're getting somewhere, while still being slow enough to allow you to enjoy the scenery/get that "I'm leaving the Shire and I won't be coming home soon." feeling xD
PC l NA Legends never die
They're written down in eternity
But you'll never see the price it costs
The scars collected all their lives
When everything's lost, they pick up their hearts and avenge defeat
Before it all starts, they suffer through harm just to touch a dream
Oh, pick yourself up, 'cause
Legends never die
I didn’t have the gold for a mount when I started years ago, before the level rewards gave you one at level 10 I think. It was maybe a year later that I bought a dlc that included one.
When I started playing the game (about 9 years ago), I wasn't aware you could train your mount. So, I walked everywhere as I didn't understand why you would use a mount
I also wondered how it was that other people were running past me on mounts. I thought it was some skill I hadn't unlocked or something like that. Well, it appears to be "something like that". Now, I use mounts a lots, expect when going on a harvest run.