As long as the repeatable missions don't have a reduced reward I don't see how it can be a problem to shorten the refresh time. If you get 600 BC for them you get them if you play the mission in 1, 2 or even 3 or more days, depending on how much you can or want to play, possibly not forgetting that you are using very valuable RL time and to use it to have fun playing or to suffer playing, to grind pixel made tanks that you can probably live without if you don't have fun grinding them, are completely different uses of your spare time.
Shortening the refresh time is an advantage for who can/want to play a lot of time and better if he is also a very good player, as in PvP being able to get very good results some missions are not so long, for who almost constantly get 7-10 kills in Glops it is way faster then getting kills in PvE as they should be 35-50 each mission. For those that need more time the reward is anyway 600 BC, at the rate they feel to play.
Now if 600 BC are a good enough reward for missions like doing 450K damage is the real problem, does not matter how short is the refresh time. Playing PvE, as some players can not or don't like to play PvP, it is 20 missions with an average of 22.5K, pretty high for an average player and perfectly possible for a good one, so is probably 4 hours of playing, and as you have 3 different missions active and only some times they overlap, you can do 2 or more of them playing the same tanks, it can mean 12 hours to get all 3, for only 1800 BC, not even half of what is needed to progress one single rank. having 40 ranks (as the first 10 ones are easier to get) it is more then 80 days of full time (12 hours/day for a good player) work if the BP should be completed with the repeatable missions only.
But as also other sources of BC are there, not repeatable missions, BC boosters and the rest, not necessarily including spending RL money, the time to complete the BP can be a lot less of that, there is plenty of time for doing it even without making playing AW a full time work, surely not playing AW for less then an hour only some evenings, but to have to complete the repeatable missions fast so you don't loose the ones that you can get the next day is a completely fast problem, let the people that has a lot of time to play do it, and if you can't or don't want to play so much time it is still possible to get the last BP reward.
As the BP this time is in the spring/summer time I suspect that I will have more fun driving my motorcycle then shooting at pixel tanks, so probably I will not reach the highest rank, but it is a deliberate choice of mine...
