I leveled most of my skills while doing the content from vr1 to vr14.
When I hit vr14 I only had some mages guild, undaunted and all alliance skills left to level.
(There also were the second morphs left.)
How good is spell scar, in terms of XP per hour?
I leveled some of my skills with repeatables in Cyrodiil:
Just put 5 of the skills you want to level on your 2nd bar and switch weapons when turning in the quests.
Cheydinhal, Cropsford and Bruma give you like 150k XP in 1.5 h.
(without PvP)
Chorrol/Waynon and Vlastarus are less worthwhile since they send you across the whole map.
I just went to spell scar on my new templar as soon as i hit vr1 in coldharbour.
My intent was to rank up some skills then park him till 1.6 and finish gold/silver then for the cp. With very little hassle i am now vr3 and have literally every single skill in every single skill line to the point of morph as a minimum.
I didnt group at all. Just solo pulled mobs (vampire/carve then vsampire/impulse). Mons are high xp and easy to manage at vr1 even.