So, in short term, betting on small odds is better. Because it causes you to play for a longer time (especially when you have not a big bankroll)
In long term, there is no difference. (Those gamblers who play for long term usually have big bankrolls and can afford to lose even more than 20 times in a row)
you said short term ? short terms means you play for a short period of time so your supposed to bet on higher odds so that you can win or loss quickly but betting in smaller odds is indeed good for smaller bankrolls so that you can minimize your chance of loosing but itll make you also play longer . loosing 20 times in a row can be acceptable or not depending on your bets . i can play longer but i dont have a big bankroll , its only a matter of bankroll management .
Short term and long term is not the amount if you ask me, its the time and the wagered amount. Just to give an example if you gamble with 1k satoshi for a whole day on all automatic you will still get at most 1-2 btc (or maybe more I don't really know the speed) but if you gamble 100 satoshi for 1 month you will gamble a lot more. Which is why I personally think its the wagered time instead of wagered amount.
You can gamble 10 btc all at once and win or lose the same amount, that is just once and you won't find out the average loss expectancy that way, however if you bet 1 million times with 100 satoshi over a month period then you will get to the 1% house edge average for sure. You won't also lose much and still have a high wagered amount that would help you out.