When doing most sidequests in HW, I easily met MSQ level reqs. As I was catching-up from a hiatus, I was lvl 62 when starting SB, did NO sidequests aside from blue+s, and didn't have enough exp for the MSQ when I was returning to Doma. Ran into that again before Castrum Abania. A couple roulettes fixed it, but I'd gone from ahead to behind because I'd stopped doing sidequests, and usually no roulettes while leveling (a grind I save for later).

On an alt with the Road to 60, I ignored most sidequests until SB--did a few that gave specific rewards like emotes or minions. Blue+s as needed. Hit 60 before the Vault, alt was 62 when starting SB. I did every SB sidequest in each area. Hit lvl 70 in Castrum Abania. Haven't touched roulettes, only doing story required dungeons/trials.

I do think sidequest exp adds up due to quantity, and some of the rewards are decent (and resellable on the MB). If someone doesn't like doing roulettes, sidequests are a viable way to keep up with MSQ.