I know there have been a few threads about this. I thought It would be useful to put some numbers on things: 

Baldr's guide has a really useful guide to full happy jumps, but they are very expensive. If you can spare $27M every couple of days, happy jumps with EDVDs will get your stats up quicker than anything. But if it takes you a week or longer to save up, you can gain stats faster and more cheaply with a 'lite' version of the happy jump. There are various versions of this, increasing in effectiveness and cost depending on what candy you use. The Lolly Jump is the cheapest but even the most expensive 'Reindeer Jump' costs less than a third of a full happy jump and gives you  roughly half the gains. I've used Vladar's excellent training outcome spreadsheet to give some examples. As these are aimed at new players, I've used a PI with 3000 happy, stats of 100k in total and the first medium-weight gym for the examples. I've only listed the Lolly Jump and Reindeer Jump, but you can use Vladar's spreadsheet to compare using Tootsie rolls or whatever.

Firstly, for comparison, the full happy jump: 4 xanax, 5 EDVDs, 1 ecstasy, 25 point refill. (31000 happy)

Cost	Gains	Cost Per stat point
$26.8M	10080	$2659

The 'Lolly Jump':  3 xanax 48 lollys, 1 ecstasy (8400 happy)

Cost	Gains	Cost Per stat point
$2.5m	2508	$997

 

'Reindeer Jump'  3 xanax, 48 reindeer droppings (or choc truffles) 1 ecstasy  (14600 happy)

Cost	Gains	Cost Per stat point
$7.5M	4078	$1839

 

The cost per stat point is just for comparison. Obviously, the lowest cost per point is to just train away all your E every 5 hours, which costs nothing but is incredibly slow. This is about balancing stat gains with your income. So if you have $2.5M a day income after rent etc, you can do a reindeer jump every 3 days, but a full happy jump only every 11 days and the reindeer jump will increase your stats more quickly.

There will be an optimum mix of happy jumps, lite jumps etc which will give you the fastest stat increase for any income. I haven't gone as far as working that out as it seems like total micromanagement., but this is the general principle, with some numbers attached.

EDIT: Ninja has done some more sums and reckons the cut-off when this stops being more efficient is at about total stats of 1M. I haven't checked, but that seems about right. Thanks Ninja

EDIT 2: Thanks for the thumbs. A couple of things. I don't think,and I could be wrong, that it is ever effective to use lollies or even big choc boxes for a 'jump' In saving up 900 or 1000 e, you are sacrificing your natural energy regen: I've sort of stopped looking into this as my stats are bit higher now. But even at low levels, it doesn't really make sense to save up lots of xanax and then just do 50 lollies. You'd be much better off waiting until the timer is at 00, 15, 30 or 45 and just maxing out your booster cooldown with lollies, training away your e, taking a xan, training, then doing an energy refill. I will come back to this and do the sums, but I've sort of moved beyond where this guide is actually useful to me,
I think that if your total stats are below about 500k, it's worth doing some form of candy jump. But basically it becomes somewhat marginal quite quickly.
What I would call 'basic' training is to just eat candy, do an ecs and train away your 400 e, then refill. This gives you 550 e with boosted happy and over the nexr 24 hours you can train away another 1200 or so from natural energy regen and xan. Basic training like this lets you train away about 1800 e per 24hrs,of which the first 550 will be boosted with some happy gain.. In doing a 'jump' (getting e to 1000, boosting happy and then doing a mandy to double it) is NOT always going boost you stats faster and cheaper than just training away the roughly 1800 e you could have had in the same time through natural e replenishment. If anyone wants to cut, paste and edit this, feel free, But basically, I've grown out of my own guide!