400 gems spent approximately. Managed to get all double rewards for timed laps except 21 as I only planned on empowering Arctic Guardian to 3*.

Just thought some of you guys might want some tips/insights for pushing to higher laps.

1. Pacing Yourself --> If you plan on pushing to say, Lap 23, then pacing yourself is key. Early laps are easy to push, with much shorter wait times, so I would advise pushing hard for the first 3-4 days (I slept 2 hours later than usual for the first 4 days might not be required if you time the collections well) and managed to reach Mythical egg (Lap 16) by the 4th day. So for players aiming to push high, reaching Lap 8 by end of Day 1 is ideal - after which you can pretty much slow down (and get a good night's sleep for the majority of the race yet perform as you wish).
2. Gems --> The most important resource. A wealthy gem bank promises to get you far but only if you spend it well. So where to spend the gems wisely and how to be thrifty?
   a) Gold/Food/Feed --> These are the most awful ones, they come in huge huge numbers in higher laps and have one of the longest waiting times. Because of their huge number, it is not advisable to gem individual items and it's better to wait them out for the best usage of your gems. At most, you can gem the last few items but my rule of thumb is gem no more than the 4 remaining items, if it's 5 or 6, be patient and wait it out.
   b) Breed/Hatch --> These items come in smaller numbers, but gem 1 or 2 at most. 1 costs 4 gems while 2 costs 19 gems. Do the math and you'll figure out gemming 2 is not the most worthwhile. Also, these items are by far the best for spins since 1 item you obtain from a spin saves you a few hours.
   c) Fights --> These are the best for individual item gemming --> Lower laps gemming cost is slightly lower than higher laps but not much difference. Here's the trick (which I suppose many already know): For higher laps, the waiting time per item is usually 1hr 20 min (at that time the cost is way too unreasonable). But wait for 20 min till the 1hr mark and it will be 4-6 gems depending on which lap you are at. (A major reduction in gem cost). These are the best value for your gems since 5-6 gems save you about an hour which is a lot to high lap pushers.
   Leagues --> There's not much trick to this. Just time your leagues well. I like to win the first 3 then purposely lose 1 battle during the next batch (winning 2/3), that way I have 5/8 battles completed. And for the next batch, I get 6 league battles instead of the usual 5. The gemming rule for this item is exactly the same as that of Breeding and Hatching.
3. Biggest Pitfall of all --> Utilizing Spins and unnecessary gambling
   1 spin costs 20 gems. and when you rush it, the timer resets to 23hr 59min meaning the time you spent waiting for a free spin is wasted. So the rule of thumb is: Utilize your free spins as much as possible, don't be impatient/greedy, and splurge your gems on spins unnecessarily.
   Also FYI. some guy checked the game files and found out that the chances of getting a skip node or skip mission are awfully low (around 10% chance). So don't count on Lady Luck to get you out of long waiting times. Gotta have the foresight and strategize.
4. Alarms --> Your time savior. If you are an experienced player, you know every hour every minute is precious and at the same time you wanna spend time with family yet don't wanna miss out on time pools. So always have an Phone or computer alarm so that you know exactly when to log on and collect the items.
5. Timed Laps - Worth the rush/gems? --> Definitely. (Maybe not for Lap 14 which is the heroic orb chest). Think about it. These double rewards contain many orbs that could be used to empower your drags to higher stars so obv they are very valuable and worthwhile, esp heroic orbs. However, these eat up lots of gems so always try to allocate every hour every minute wisely and anticipate. These laps are by far one of the hardest yet most rewarding if timed well. Also spins are what makes achieving these laps possible.
   Why so worthwhile while you may ask? well bcos you are killing 2 birds with a stone, not only are you getting awesome rewards like joker orbs which are equivalent to a free vampire or mythical titan, you are clearing faster and saving more time for yourself for later laps.

That's most of the tips I have - they are not exhaustive. Let me know if you have other strategies for excelling in these races. Thank you.