more mass is inserted than desired when insert/pack command is used with keyword "insert_every"

Hello Community

I have a question related to insert/pack command in Liggghts. I want to generate a dense packing of polydispersed particles (density 2650kg/m3) in certain region of my domain (region bc). I find is that the mass of particle injected is much higher (when "insert_every 1000" is used) and fill whole geometry intead of desired region (bc). On the other hand, when "insert_every once" is used the expected mass in the region is obtained without any problem but some particles are also thrown out of the region bc. To give you an idea, here is the list of command for generating dense pack:
case 1: when particles are inserted in a defined region @every 1000 time steps till the desired solid fraction in the region is achieved.
region bc block 0.0 0.3 0.0 0.1 0.0 0.3 units box
fix ins all insert/pack seed 91428863 distributiontemplate pdd1 vel constant 0. 0. 0. insert_every 1000 overlapcheck no all_in yes volumefraction_region 0.5 region bc
case 2: when particles are inserted in a defined region once till the desired solid fraction in the region is achieved.
region bc block 0.0 0.3 0.0 0.1 0.0 0.3 units box
fix ins all insert/pack seed 91428863 distributiontemplate pdd1 vel constant 0. 0. 0. insert_every once overlapcheck no all_in yes volumefraction_region 0.5 region bc

In both the cases, solid fraction of 0.5 in the region bc, should have resulted 11.925kg particles (=0.5*0.3*0.1*0.3*2650). What I actually get is very different than what I want. for case 1, a total of 41.67 kg particles and injected (till 30000 time steps) and the insertion stops and particle settled. the ouput form log file is:
INFO: Particle insertion ins: inserted 352 particle templates (mass 1.106831e-01) at step 30001
- a total of 132019 particle templates (mass 4.166810e+01) inserted so far.
31000 130360 0.77722198 0.3359016 0.059024 ...

for case 2, a total of 11.92 kg of particles are injected at once. The output says:
INFO: Particle insertion ins: inserted 37794 particle templates (mass 1.192620e+01) at step 1
- a total of 37794 particle templates (mass 1.192620e+01) inserted so far.
1 37794 4.9705751 0 0.059024 ...

In my understanding, both cases should should have resulted the same mass but only difference is that "insert_every 1000" should inject particles at specified times till the desired mass is achieved. I wonder, why keyword "insert_every" results that kind of strange behavour?

Best Regards
Atul