I always think loyalty is very subjective to your own personal play style, what works for one doesn't for another. My play style has changed over the past couple of years, but a couple of years back I was playing £1-£5 spins, depositing £200+ every time, sometimes (although not often) £2000 a day, regularly £500+ a day though. VS's rewards were nothing to me, yes I would get £10-15 cashback, maybe £25 on the race, and the odd few 5/10 spins from the battles, but that was pretty much nothing compared to my play style. 10 spins on a 10p game didn't even cover the cost of 1 spin the way I was playing. If anything it used to annoy me as if it was on a game I play, for example at the time it could have been Doa, and I usually play at 90p, then get a wildline on a 9p free spin, I would be extremely pissed off lol.
It can also depend on you winning or losing. I stuck £20 in Coral about 6 months ago, and after a few hours got up to £2200. On that day (was once a week then) they gave 25% extra cash (0x wagering) on any winnings over £100 up to £2000, so I got an extra £500 for being lucky from a £20 deposit. I didn't get that much from Videoslots the last 4 months of playing, and making deposits of around £6k. They would also do 25% on losses up to £2000 at the time too, which I got £100 from a few times, again cash, no wagering.
SkyVegas used to give regular 25% deposit bonuses up to £100 (so deposit 400 get 100 bonus) with 5x wagering bonus only. So in effect they were giving you 25% with 1x D&B wagering. I used to just deposit the £400 and play 250 x £2 spins on Bonanza, it was rare I ended up under the £400 deposit, but regularly withdrew with a profit.
I personally look at loyalty as to the base value though. If a casino gives you 50 x 10p spins, then they have gave you £5. If you happen to win £500 using those spins, they didn't give you £500 they gave you £5 that you won from. I know some people look at it the other way round, but as much as once in a blue moon you might get a withdraw from 10 free spins or something, almost every time you don't.