I belive it's really a personal thing on how you like to rollover your bonuses but I like to share how I have done things since the beginning of sportsbooks online (I dont want to say this is correct or anything but atleast I have had good success with this method.)

First of all the bookmakers biggest goal is to get you to loose your deposit + your bonus, dont think anything else.

Their bonus terms & conditions gets tougher and tougher. I remember back in the days when Gamebookers gave out a 100% deposit bonus on 100€ with 1x rollover req. so you could actually not loose any money.

These days we have to be considered lucky if we get 3x rollover. With this said I still belive that you can be really succesful interms of earning money by collecting bonuses.

I'm a gambler by nature I as many others out there can't really "feel" the money actually being there once it's online. So this is how I do my bonus business!

I belive the bookmakers feel that they get you eventually if you play there long enough so I play hard once I start...My goal is to clear the bonus as soon as possible and have some extra money to withdraw.
I don't belive in grinding during a long time to clear the bonus. So ok I basicly never use anything else then 100% deposit bonuses/freebets, the rest for me is just annoyingly little especially when you take in the factors that everytime you signup clear bonus and want to withdraw they most likely aint gonna like it and start to bitch about ID's,bills & creditcards. So when I decide to jump a new bookmaker im always ready to be checked and never abuse the bonus in anyway like multiple accounts etc. even tho it might be possible its just a waste of time imo. Get good in betting and there is no need to do such things.

Bonus example

100% deposit bonus up to 100€ 3x rollover deposit + bonus. Atleast 2.0 odds req.

So we need to clear 200(100 deposit+100 bonus) x 3 = 600 euro. Some people might find this alot because of how they usually bet but for me its little. Think positive think that you only risk 100 euro but you have 200 large to play with.  My favorite sport to clear bonuses on are baseball. Always high odds thanks to runlines. (-1.5) and really hard for bookmakers to correctly predict over/under lines there aswell.
I do this in 2 diffrent ways. I either take the hole 200 cake bet it on a game which I feel really safe about or I split the cake in 2 and bet 100 to get 2 shots at winning 1 game. Because since you only touch games that are above 2 in odds you only need to make 1/2 games to stay alive. You do that if you have some sort of talent and ofcourse not being the most unlucky person on the planet.

So I bet 200€ on Phillies (-1.5) against Astros to the odds 2.35. I feel comfortable knowing that Phillies thanks to better form, better pitcher, better offensive  takes this game fairly easy.

Phillies win this game and I win the bet I have 475€ fresh ones on my account (I still have only deposited(risked) 100€ and my rollover req. is 400€ left of.
Now I change tactic, I know I will make a profit now. I know myself and that I usually win over 50% of the matches I bet on baseball fairly easy and they are all gonna be well above 2 in odds.

So I say to myself I bet 100€ per game now so I need to do 4 games to clear the rollover (no need to rush at all)  be picky and play on stuff you really have a good knowledge about...
For me a bad result would be 50% win  that would equal to (if the avarage odds is 2.35) that I would have 

Bet won: 100 x 2.35 = 475 + 135 =  610
Bet loss: -100 = 610-100 = 510
Bet won: 100 x 2.35 = 510 + 135 = 645
Bet loss: -100 = 645-100 = 545

Final result of 545€ on sportsbook account with all the rollover completed.

If your really not that good and/or unlucky you can end up just winning 1 outta 4 games its still enough for you to have 310€ on your sportsbook account (with only 100€ deposited)...

Remember this is not failsafe, this is how I do it and that doesn't mean it's the correct way. Rembember to only bet with money that you can afford to loose.